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102-649: Comcast Center , also known as the Comcast Tower , is a skyscraper at 1701 John F. Kennedy Boulevard in Center City Philadelphia . The 58-story, 297-meter (974 ft) tower is the second-tallest building in Philadelphia and in the U.S. state of Pennsylvania , and the 31st-tallest building in the United States . Originally called One Pennsylvania Plaza when plans for the building were announced in 2001,

204-663: A Buttressed core . Trussed tube and X-bracing: Richard Tenguerian Richard Tenguerian was born in Aleppo , Syria . His parents are survivors of the Armenian genocide . His father, Antranig Tenguerian, was a sculptor and his mother, Mary Tenguerian, was a fashion designer who worked for Chanel Studio in Lebanon . At age 14, while attending school, Richard entered a summer internship program with one of Lebanon's leading architectural firms, where he made his first model. He applied to

306-497: A 60-story, 962 feet (293 m) tower, making it the tallest building in the city at the time. In the redesign, the kasota stone was changed to a lighter granite and a short pyramidal roof was added. The redesign was a result of discussions that had begun in 2003 with Comcast about moving into the tower. On January 3, 2004, Liberty Property Trust signed a 15½-year lease with Comcast and a construction contract with L.F. Driscoll Co. Liberty Property Trust also unveiled another redesign of

408-581: A KOZ designation for the skyscraper could generate US$ 27 million for the city. Critics of the KOZ designation also claimed that close relationships between Liberty Property Trust and Comcast and the Rendell administration were inappropriately influencing the governor's position on the issue. When Rendell was mayor of Philadelphia, David L. Cohen , a Comcast executive vice president, was Rendell's chief of staff, and William P. Hankowsky, Liberty Property Trust's chief executive,

510-469: A background designed to mimic wood paneling of the walls of the lobby. Another part of the installation displays images of cranes and machinery forming the design of a clock that tells the correct time of day. The Comcast Experience quickly became a popular tourist attraction, prompting city officials to add the Comcast Center to its tourism website. Between Thanksgiving 2008 and New Year's Day 2009,

612-533: A championship following the construction of buildings taller than the statue of William Penn on top of the 548-foot (167 m) Philadelphia City Hall . The 25-inch (64 cm) statue of William Penn remained on the beam until it was stolen. The statue was replaced and the "curse" ended when the Philadelphia Phillies won the 2008 World Series . The Comcast Center officially opened on June 6, 2008. A study sponsored by Comcast and Liberty Property Trust said

714-537: A city consisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen . Shibam was made up of over 500 tower houses, each one rising 5 to 11 stories high, with each floor being an apartment occupied by a single family. The city was built in this way in order to protect it from Bedouin attacks. Shibam still has the tallest mudbrick buildings in the world, with many of them over 30 m (98 ft) high. An early modern example of high-rise housing

816-459: A father and son. Comcast is the skyscraper's largest tenant, leasing 1,094,212 square feet (101,656 m), or 89 percent of the building. The second-largest tenant is Citizens Bank of Pennsylvania, which leases 56,000 square feet (5,200 m) of office and retail space. Other tenants include the Judge Group, a staffing agency, which leases 6,427 square feet (600 m). Comcast's office space

918-467: A holiday video was included as part of the installation. The second piece of art is Jonathan Borofsky 's Humanity in Motion . Located in the glass atrium of the winter garden, Humanity in Motion shows ten life-size human figures walking across ten horizontal poles positioned at different levels of the atrium. At ground level, looking up at the stainless steel figures, are two more figures shaped to look like

1020-733: A more classical approach came back to global skyscraper design, that remains popular today. Examples are the Wells Fargo Center , NBC Tower , Parkview Square , 30 Park Place , the Messeturm , the iconic Petronas Towers and Jin Mao Tower . Other contemporary styles and movements in skyscraper design include organic , sustainable , neo-futurist , structuralist , high-tech , deconstructivist , blob , digital , streamline , novelty , critical regionalist , vernacular , Neo Art Deco and neohistorist , also known as revivalist . 3 September

1122-399: A particularly small surface area of what are conventionally thought of as walls. Because the walls are not load-bearing most skyscrapers are characterized by surface areas of windows made possible by the concept of steel frame and curtain wall. However, skyscrapers can also have curtain walls that mimic conventional walls and have a small surface area of windows. The concept of a skyscraper is

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1224-420: A product of the industrialized age , made possible by cheap fossil fuel derived energy and industrially refined raw materials such as steel and concrete . The construction of skyscrapers was enabled by steel frame construction that surpassed brick and mortar construction starting at the end of the 19th century and finally surpassing it in the 20th century together with reinforced concrete construction as

1326-454: A proto-skyscraper, or to New York's seven-floor Equitable Life Building , built in 1870. Steel skeleton construction has allowed for today's supertall skyscrapers now being built worldwide. The nomination of one structure versus another being the first skyscraper, and why, depends on what factors are stressed. The structural definition of the word skyscraper was refined later by architectural historians, based on engineering developments of

1428-412: A proud and soaring thing, rising in sheer exaltation that from bottom to top it is a unit without a single dissenting line. Some structural engineers define a high-rise as any vertical construction for which wind is a more significant load factor than earthquake or weight. Note that this criterion fits not only high-rises but some other tall structures, such as towers . Different organizations from

1530-556: A skyscraper today, it was record setting. The building of tall buildings in the 1880s gave the skyscraper its first architectural movement, broadly termed the Chicago School , which developed what has been called the Commercial Style. The architect, Major William Le Baron Jenney , created a load-bearing structural frame. In this building, a steel frame supported the entire weight of the walls, instead of load-bearing walls carrying

1632-417: A small surface area of windows. Modern skyscrapers often have a tubular structure , and are designed to act like a hollow cylinder to resist wind, seismic, and other lateral loads. To appear more slender, allow less wind exposure and transmit more daylight to the ground, many skyscrapers have a design with setbacks , which in some cases is also structurally required. As of September 2023 , fifteen cities in

1734-514: A time, the tallest of which is the 97.2 m (319 ft) high Asinelli Tower. A Florentine law of 1251 decreed that all urban buildings be immediately reduced to less than 26 m. Even medium-sized towns of the era are known to have proliferations of towers, such as the 72 towers that ranged up to 51 m height in San Gimignano . The medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in

1836-477: A vacant lot into a transit gateway. Skyscraper A skyscraper is a tall continuously habitable building having multiple floors. Modern sources define skyscrapers as being at least 100 meters (330 ft) or 150 meters (490 ft) in height, though there is no universally accepted definition, other than being very tall high-rise buildings . Skyscrapers may host offices, hotels, residential spaces, and retail spaces. One common feature of skyscrapers

1938-466: A variety of shapes, and it could be riveted, ensuring strong connections. The simplicity of a steel frame eliminated the inefficient part of a shear wall, the central portion, and consolidated support members in a much stronger fashion by allowing both horizontal and vertical supports throughout. Among steel's drawbacks is that as more material must be supported as height increases, the distance between supporting members must decrease, which in turn increases

2040-469: A vertical tube-like structural system capable of resisting lateral forces in any direction by cantilevering from the foundation". Closely spaced interconnected exterior columns form the tube. Horizontal loads (primarily wind) are supported by the structure as a whole. Framed tubes allow fewer interior columns, and so create more usable floor space, and about half the exterior surface is available for windows. Where larger openings like garage doors are required,

2142-547: Is a 110 feet (34 m) tall winter garden . The winter garden entrance directly connects to the underground concourse of Suburban Station . The building also has a lobby entrance that leads to the Arch Street Presbyterian Church adjacent to the tower. The exterior lighting scheme of the building was designed by Quentin Thomas Associates, and consists primarily of white LEDs color-temperature matched to

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2244-704: Is having a steel frame that supports curtain walls . This idea was invented by Viollet le Duc in his discourses on architecture. These curtain walls either bear on the framework below or are suspended from the framework above, rather than resting on load-bearing walls of conventional construction. Some early skyscrapers have a steel frame that enables the construction of load-bearing walls taller than of those made of reinforced concrete . Modern skyscraper walls are not load-bearing , and most skyscrapers are characterized by large surface areas of windows made possible by steel frames and curtain walls. However, skyscrapers can have curtain walls that mimic conventional walls with

2346-406: Is important in most building design, but particularly for skyscrapers since even a small chance of catastrophic failure is unacceptable given the tremendous damage such failure would cause. This presents a paradox to civil engineers : the only way to assure a lack of failure is to test for all modes of failure, in both the laboratory and the real world. But the only way to know of all modes of failure

2448-433: Is largely from the force of the building material itself. In most building designs, the weight of the structure is much larger than the weight of the material that it will support beyond its own weight. In technical terms, the dead load , the load of the structure, is larger than the live load , the weight of things in the structure (people, furniture, vehicles, etc.). As such, the amount of structural material required within

2550-399: Is the global commemorative day for skyscrapers, called "Skyscraper Day". New York City developers competed among themselves, with successively taller buildings claiming the title of "world's tallest" in the 1920s and early 1930s, culminating with the completion of the 318.9 m (1,046 ft) Chrysler Building in 1930 and the 443.2 m (1,454 ft) Empire State Building in 1931,

2652-419: Is to learn from previous failures. Thus, no engineer can be absolutely sure that a given structure will resist all loadings that could cause failure; instead, one can only have large enough margins of safety such that a failure is acceptably unlikely. When buildings do fail, engineers question whether the failure was due to some lack of foresight or due to some unknowable factor. The load a skyscraper experiences

2754-564: The American University in Beirut , but the 1975 Lebanese Civil War thwarted his intentions. At age 21, Richard visited a relative in New York and was intrigued by the opportunities the city offered . He began working as a model maker, and built a reputation in the architectural community, which helped him finance his undergraduate education. He earned a bachelor's degree in architecture from

2856-711: The Pratt Institute . Encouraged by the high demand for model makers in the architectural community, Richard started his own company, becoming a pioneer in the field . Early on in his career, he was contacted by the legendary architect Philip Johnson , who sought his services, thus paving his way to greater accomplishments . In addition to various projects in the United States, he has created models for buildings in Dubai, Kuwait, Saudi Arabia, Singapore, Indonesia and England. He has also developed models for clients in Russia, South America,

2958-629: The " Seven Sisters ", were built between 1947 and 1953; and one, the Main building of Moscow State University , was the tallest building in Europe for nearly four decades (1953–1990). Other skyscrapers in the style of Socialist Classicism were erected in East Germany ( Frankfurter Tor ), Poland ( PKiN ), Ukraine ( Hotel Moscow ), Latvia ( Academy of Sciences ), and other Eastern Bloc countries. Western European countries also began to permit taller skyscrapers during

3060-460: The 10th century described as resembling minarets . Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, with roof gardens on the top floor complete with ox-drawn water wheels for irrigating them. Cairo in the 16th century had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants . An early example of

3162-465: The 1880s that had enabled construction of tall multi-story buildings. This definition was based on the steel skeleton—as opposed to constructions of load-bearing masonry , which passed their practical limit in 1891 with Chicago's Monadnock Building . What is the chief characteristic of the tall office building? It is lofty. It must be tall. The force and power of altitude must be in it, the glory and pride of exaltation must be in it. It must be every inch

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3264-580: The 1960s now use a tube design derived from Khan's structural engineering principles, examples including the construction of the World Trade Center , Aon Center , Petronas Towers , Jin Mao Building , and most other supertall skyscrapers since the 1960s. The strong influence of tube structure design is also evident in the construction of the current tallest skyscraper, the Burj Khalifa , which uses

3366-587: The 1960s, according to the CTBUH, the skyscraper has been reoriented away from a symbol for North American corporate power to instead communicate a city or nation's place in the world. Skyscraper construction entered a three-decades-long era of stagnation in 1930 due to the Great Depression and then World War II . Shortly after the war ended, Russia began construction on a series of skyscrapers in Moscow . Seven, dubbed

3468-807: The 26th century BC. It was not surpassed in height for thousands of years, the 160 m (520 ft) Lincoln Cathedral having exceeded it in 1311–1549, before its central spire collapsed. The latter in turn was not surpassed until the 555-foot (169 m) Washington Monument in 1884. However, being uninhabited, none of these structures actually comply with the modern definition of a skyscraper. High-rise apartments flourished in classical antiquity . Ancient Roman insulae in imperial cities reached 10 and more stories. Beginning with Augustus (r. 30 BC-14 AD), several emperors attempted to establish limits of 20–25 m for multi-stories buildings, but were met with only limited success. Lower floors were typically occupied by shops or wealthy families, with

3570-603: The 52- story One Pennsylvania Plaza in Center City . Anticipated US$ 400 million, One Pennsylvania Plaza was to be 750 ft (230 m) and made of kasota stone similar to the Philadelphia Museum of Art . The site for the future skyscraper was situated at 17th Street and John F. Kennedy Boulevard , a site occupied by a building that housed the Defender Association of Philadelphia and a parking lot. Demolition of

3672-666: The 57 m (187 ft) tall 1924 Marx House in Düsseldorf , the 65 m (213 ft) tall Borsigturm in Berlin , built in 1924, the 65 m (213 ft) tall Hansahochhaus in Cologne , Germany, built in 1925; the 61 m (200 ft) Kungstornen (Kings' Towers) in Stockholm , Sweden, which were built 1924–25; the 77 m (253 ft) Ullsteinhaus in Berlin, Germany, built in 1927;

3774-596: The 89 m (292 ft) Edificio Telefónica in Madrid , Spain, built in 1929; the 87.5 m (287 ft) Boerentoren in Antwerp, Belgium, built in 1932; the 66 m (217 ft) Prudential Building in Warsaw , Poland, built in 1934; and the 108 m (354 ft) Torre Piacentini in Genoa , Italy, built in 1940. After an early competition between New York City and Chicago for

3876-559: The CTBUH, is the distance between the highest floor and its architectural top (excluding antennae, flagpole or other functional extensions). Vanity height first appeared in New York City skyscrapers as early as the 1920s and 1930s but supertall buildings have relied on such uninhabitable extensions for on average 30% of their height, raising potential definitional and sustainability issues. The current era of skyscrapers focuses on sustainability , its built and natural environments, including

3978-462: The Cira Centre, another skyscraper in the KOZ controversy, were filled by corporations moving from other Center City office towers, the city could lose US$ 153 million by 2018. A report released by the group of building owners opposed to KOZ says the two buildings could cost the city almost US$ 91 million a year. In contrast, a report issued by a consulting company hired by Liberty Property Trust said that

4080-421: The Comcast Center to German real estate firm CommerzLeasing & Immobilien AG, a subsidiary of Commerzbank AG . The deal completed Liberty Property Trust's planned recapitalization of the anticipated cost of the building, and the value of the joint venture, called Liberty/Commerz 1701 JFK Boulevard L.P., included mortgage debt and equity. On June 18, 2007, the Comcast Center was topped out . The ceremony, which

4182-525: The Comcast Center went through two redesigns before construction began in 2005. Comcast Center was designed by Robert A.M. Stern Architects for Liberty Property Trust . In early 2005, the final redesign and its new name—the Comcast Center—were unveiled. The building is named after its lead tenant, cable company Comcast , which makes the skyscraper its corporate headquarters. Leasing 1,094,212 square feet (101,656 m), Comcast takes up 89 percent of

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4284-485: The Comcast Center. 16,500 square feet (1,500 m) of retail space is on the underground concourse while the rest is located on the street level. The building features high ceilings with some floors having a ceiling height of 13 feet (4 m). The lower floors on the south side of the building feature four three-story stacked atrias . The building also features a 500-seat concourse level dining court and an 87-space private underground parking garage. ThyssenKrupp provided

4386-407: The United States and Europe define skyscrapers as buildings at least 150 m (490 ft) in height or taller, with " supertall " skyscrapers for buildings higher than 300 m (984 ft) and " megatall " skyscrapers for those taller than 600 m (1,969 ft). The tallest structure in ancient times was the 146 m (479 ft) Great Pyramid of Giza in ancient Egypt , built in

4488-497: The amount of material that must be supported. This becomes inefficient and uneconomic for buildings above 40 stories tall as usable floor spaces are reduced for supporting column and due to more usage of steel. A new structural system of framed tubes was developed by Fazlur Rahman Khan in 1963. The framed tube structure is defined as "a three dimensional space structure composed of three, four, or possibly more frames, braced frames, or shear walls, joined at or near their edges to form

4590-529: The building and its new name, the Comcast Center. The now 975-foot (297 m), 58-story Comcast Center would no longer have a pyramid top and would have a complete glass facade . The architectural model was created by Richard Tenguerian . Liberty Property Trust hoped to get the One Pennsylvania Plaza site designated a Keystone Opportunity Improvement Zone (KOZ). KOZ designation was intended to encourage development in poor, blighted areas by exempting

4692-439: The building and the offices for the Comcast Center's second-largest tenant, Citizens Bank of Pennsylvania, were new to the city. The Comcast Center has 58 floors, 56 of which are usable. The structure of the Comcast Center comprises a central concrete core with steel-framed floors. The building's exterior features a glass curtain wall made of lightly tinted, non-reflective low-emissivity glass. The tower tapers inward towards

4794-479: The building began in 2002 and ended in 2003. Cable company Comcast had been looking for possible new headquarters space in anticipation of the end of its lease in Centre Square in 2006. Comcast was looking for more than 400,000 square feet (37,000 m) of office space and developers were actively courting the company for their developments. Comcast was the only employer in the city with major expansion plans at

4896-410: The building's waterless urinals . The waterless urinals were part of the plan to make the Comcast Center an environmentally friendly building because they would save an extra 1.6 million US gallons (6,100 m) of water a year. The plumbers union opposed the waterless urinals, claiming they were unsanitary and would provide less work for the plumbers. Philadelphia's Plumbing Advisory Board approved

4998-466: The building's 30 gearless elevators , seven hydraulic elevators, and two escalators . The Comcast Center's winter garden entrance contains two works of installation art : the Comcast Experience display and Humanity in Motion . The Comcast Experience is a 25.4 feet (7.7 m) tall, 83.3 feet (25.4 m) wide, 2,000 square feet (190 m) high-definition LED screen situated on a wall in

5100-528: The building. The building features retail and restaurant space and a connection to the nearby Suburban Station . In Comcast Center's lobby is the Comcast Experience , which is a 2,000-square-foot (190 m) high-definition LED screen that has become a tourist attraction. Designed to be environmentally friendly , the skyscraper is the tallest Leadership in Energy and Environmental Design (LEED) certified building in Philadelphia. In 1999, class-A office vacancy in

5202-546: The city was at 6.6%, leading developer Willard Rouse to envision a new tower. Eventually the developer settled on the location where he constructed this building, a 2-acre (8,100 m), $ 288 per square-foot parcel owned by Equitable Life Assurance Co. In 2000, the architect and Driehaus Prize winner Robert A. M. Stern began working on a design for a skyscraper being planned by Liberty Property Trust in Philadelphia . In 2001, Liberty Property Trust announced its plan to build

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5304-531: The city, responsible in its treatment of the environment". She felt the tower's shape reminded her of a giant flash drive . Saffron said the building excelled at the street level, praising the plaza, concourse, and its connection to Suburban Station. In 2009, the Comcast Center was awarded the Urban Land Institute Award for Excellence in the Americas category for the transformation of what was once mostly

5406-423: The city. However, other Center City building owners, including Comcast's landlord at Centre Square, HRPT Properties Trust, were opposed to the plan. They said giving the tower the KOZ designation would give it an unfair advantage because Liberty Property Trust could charge above-market rents since the tax breaks would offset the cost for tenants. The group believed tenants attracted to One Pennsylvania Plaza because of

5508-424: The classical designs of the early skyscrapers , instead embracing the uniform international style ; many older skyscrapers were redesigned to suit contemporary tastes or even demolished—such as New York's Singer Building , once the world's tallest skyscraper. German -American architect Ludwig Mies van der Rohe became one of the world's most renowned architects in the second half of the 20th century. He conceived

5610-578: The construction of the Comcast Center created 17,200 jobs and generated US$ 2 billion of economic activity for Pennsylvania. Despite opposition by other building owners to construction of the Comcast Center, by the time most space in the Comcast Center had been leased vacancy rates in Center City offices were falling and rents were rising. HRPT Properties Trust had leased 70 percent of the space Comcast had vacated by 2007. The predictions by opponents did not occur mainly because Comcast ended up leasing 89 percent of

5712-644: The creation of a significant number of early skyscrapers, though none of these were steel reinforced and few remain today. Height limits and fire restrictions were later introduced. In the late 1800s, London builders found building heights limited due to issues with existing buildings. High-rise development in London is restricted at certain sites if it would obstruct protected views of St Paul's Cathedral and other historic buildings. This policy, 'St Paul's Heights', has officially been in operation since 1927. Concerns about aesthetics and fire safety had likewise hampered

5814-632: The development of skyscrapers across continental Europe for the first half of the 20th century. By 1940, there were around 100 high-rise buildings in Europe ( List of early skyscrapers ). Some examples of these are the 43 m (141 ft) tall 1898 Witte Huis (White House) in Rotterdam ; the 51.5 m (169 ft) tall PAST Building (1906–1908) in Warsaw ; the Royal Liver Building in Liverpool, completed in 1911 and 90 m (300 ft) high;

5916-402: The early 1960s Bangladeshi-American structural engineer Fazlur Rahman Khan , considered the "father of tubular designs " for high-rises, discovered that the dominating rigid steel frame structure was not the only system apt for tall buildings, marking a new era of skyscraper construction in terms of multiple structural systems . His central innovation in skyscraper design and construction

6018-416: The environment and loaded structures with decorative elements and extravagant finishes. This approach to design was opposed by Fazlur Khan and he considered the designs to be whimsical rather than rational. Moreover, he considered the work to be a waste of precious natural resources. Khan's work promoted structures integrated with architecture and the least use of material resulting in the smallest impact on

6120-454: The environment. The next era of skyscrapers will focus on the environment including performance of structures, types of material, construction practices, absolute minimal use of materials/natural resources, embodied energy within the structures, and more importantly, a holistically integrated building systems approach. Modern building practices regarding supertall structures have led to the study of "vanity height". Vanity height, according to

6222-405: The executive floors. The retail portion of the tower includes numerous shops and eateries. The shops and eateries include national and regional chains, and initially featured a restaurant called Table 31. Table 31, which had a cafe on the plaza and a restaurant spread over three floors in the tower, was owned by Philadelphia restaurateurs and chefs Georges Perrier and Chris Scarduzio. The restaurant

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6324-523: The first building in the world to feature a metal-framed glass curtain wall , a design element which creates light, airy interiors and has since been used the world over as a defining feature of skyscrapers". Further developments led to what many individuals and organizations consider the world's first skyscraper, the ten-story Home Insurance Building in Chicago, built in 1884–1885. While its original height of 42.1 m (138 ft) does not even qualify as

6426-427: The fluorescent lights used by the interior. Along each floor, the corner spandrel panels feature upward and downward-facing 4,100K LEDs to create the appearance that the length of the building has been bottom-lit by spotlights. The only major consistently active color element can be found at the top of the tuned mass damper; a single row of color-changing LEDs that is programmed to commemorate special events. For example,

6528-471: The glass façade skyscraper and, along with Norwegian Fred Severud , designed the Seagram Building in 1958, a skyscraper that is often regarded as the pinnacle of modernist high-rise architecture. Skyscraper construction surged throughout the 1960s. The impetus behind the upswing was a series of transformative innovations which made it possible for people to live and work in "cities in the sky". In

6630-465: The hundred-story John Hancock Center and the massive 442 m (1,450 ft) Willis Tower . Other pioneers of this field include Hal Iyengar , William LeMessurier , and Minoru Yamasaki , the architect of the World Trade Center . Many buildings designed in the 70s lacked a particular style and recalled ornamentation from earlier buildings designed before the 50s. These design plans ignored

6732-454: The lower levels of a skyscraper will be much larger than the material required within higher levels. This is not always visually apparent. The Empire State Building 's setbacks are actually a result of the building code at the time ( 1916 Zoning Resolution ), and were not structurally required. On the other hand, John Hancock Center 's shape is uniquely the result of how it supports loads. Vertical supports can come in several types, among which

6834-674: The most common for skyscrapers can be categorized as steel frames, concrete cores, tube within tube design, and shear walls. The wind loading on a skyscraper is also considerable. In fact, the lateral wind load imposed on supertall structures is generally the governing factor in the structural design. Wind pressure increases with height, so for very tall buildings, the loads associated with wind are larger than dead or live loads. Other vertical and horizontal loading factors come from varied, unpredictable sources, such as earthquakes. By 1895, steel had replaced cast iron as skyscrapers' structural material. Its malleability allowed it to be formed into

6936-435: The most complex encountered given the balances required between economics , engineering , and construction management. One common feature of skyscrapers is a steel framework from which curtain walls are suspended, rather than load-bearing walls of conventional construction. Most skyscrapers have a steel frame that enables them to be built taller than typical load-bearing walls of reinforced concrete. Skyscrapers usually have

7038-406: The performance of structures, types of materials, construction practices, absolute minimal use of materials and natural resources, energy within the structure, and a holistically integrated building systems approach. LEED is a current green building standard. Architecturally, with the movements of Postmodernism , New Urbanism and New Classical Architecture , that established since the 1980s,

7140-719: The price of steel decreased and labor costs increased. The steel frames become inefficient and uneconomic for supertall buildings as usable floor space is reduced for progressively larger supporting columns. Since about 1960, tubular designs have been used for high rises. This reduces the usage of material (more efficient in economic terms – Willis Tower uses a third less steel than the Empire State Building) yet allows greater height. It allows fewer interior columns, and so creates more usable floor space. It further enables buildings to take on various shapes. Elevators are characteristic to skyscrapers. In 1852 Elisha Otis introduced

7242-474: The safety elevator at the E. V. Haughwout Building in New York City, allowing convenient and safe transport to buildings' upper floors. Otis later introduced the first commercial passenger elevators to the Equitable Life Building in 1870, considered by some architectural historians to be the first skyscraper. Another crucial development was the use of a steel frame instead of stone or brick, otherwise

7344-643: The safety elevator, allowing convenient and safe passenger movement to upper floors. Another crucial development was the use of a steel frame instead of stone or brick, otherwise the walls on the lower floors on a tall building would be too thick to be practical. Today major manufacturers of elevators include Otis , ThyssenKrupp , Schindler , and KONE . Advances in construction techniques have allowed skyscrapers to narrow in width, while increasing in height. Some of these new techniques include mass dampers to reduce vibrations and swaying, and gaps to allow air to pass through, reducing wind shear. Good structural design

7446-440: The space is used for content and programing teams, customer service, Technology & Product teams, Finance and Legal. The interior design of the offices are designed with a variety of shape and color ranging from the open white space of the upper offices to the colorful walls of the training center. Other designs include a glass and stainless steel staircase that wraps around a four-story column of flat-screen monitors and connects

7548-435: The state's Department of Economic and Community Development, Comcast received US$ 12.75 million that included a US$ 4-million opportunity grant, US$ 6.75 million in job-creation tax credits, and US$ 2 million in job training assistance. Despite the failure to gain KOZ status, the project received US$ 42.75 million in financial incentives from the state. The official groundbreaking ceremony was on March 31, 2005. The ceremony, which

7650-602: The tallest LEED building in Philadelphia. The building was designed to use 40 percent less water than a typical office building, and the plaza was designed to reduce heat-island effect from the pavement by 70 percent. Reducing air conditioning and lighting costs, the low-emissivity glass curtain wall blocks 60 percent of heat while allowing 70 percent of the Sun's light inside. The skyscraper has 1,238,000 square feet (115,000 m) of rentable space, including 36,000 square feet (3,300 m) of restaurant and retail space called The Market at

7752-487: The tax breaks would cause more vacancies in other Center City skyscrapers, rather than attracting more business to blighted areas as intended under the law. In early 2004, Center City had a vacancy rate of 12.8%. Both sides of the issue hired law firms, lobbyists, and business associates to promote their positions to city and state officials. A report by the Center City District said if both One Pennsylvania Plaza and

7854-557: The tenants of the building from all state and local taxes. Designating One Pennsylvania Plaza a KOZ was supported by then Pennsylvania Governor Ed Rendell , who said it was important to keep corporations within the city. At the time, many of Philadelphia's big employers' leases, including Comcast's, were due to expire, and the employers were considering the possibility of moving out of the city and state. Rendell also said allowing Comcast to enlarge its headquarters by moving into One Pennsylvania Plaza could attract other corporate headquarters to

7956-466: The time. Comcast was considering staying in Centre Square, while also contemplating moving their headquarters to the new Cira Centre building or One Pennsylvania Plaza . Comcast was spread out over 10 floors in two buildings at Centre Square and wanted space on contiguous floors. In January 2004, Liberty Property Trust unveiled a redesign for the building. The redesign turned One Pennsylvania Plaza into

8058-438: The title for six years. The design and construction of skyscrapers involves creating safe, habitable spaces in very tall buildings. The buildings must support their weight, resist wind and earthquakes, and protect occupants from fire. Yet they must also be conveniently accessible, even on the upper floors, and provide utilities and a comfortable climate for the occupants. The problems posed in skyscraper design are considered among

8160-434: The top and features two cutouts near the top of the building on the north and south sides. The Comcast Center faces a half-acre public plaza. The plaza, designed by Lucinda Sanders of OLIN , sits over underground railroad tracks. It features a seasonal outdoor restaurant, Cafe Click, that is sheltered by a trellis. Between the cafe and the building entrance is a choreographed fountain designed by Wet . The tower's entrance

8262-505: The top would be colored pink for Breast Cancer Awareness Month . To prevent the tower from swaying too much in the wind, the Comcast Center contains a 300,000-US-gallon (1,100 m) double-chambered concrete tuned liquid column damper , the largest such damper in North America. Receiving a gold Leadership in Energy and Environmental Design (LEED) rating in April 2009, the Comcast Center is

8364-687: The tube frame must be interrupted, with transfer girders used to maintain structural integrity. Tube structures cut down costs, at the same time allowing buildings to reach greater heights. Concrete tube-frame construction was first used in the DeWitt-Chestnut Apartment Building , completed in Chicago in 1963, and soon after in the John Hancock Center and World Trade Center . The tubular systems are fundamental to tall building design. Most buildings over 40 stories constructed since

8466-474: The tube structure was the Chestnut De-Witt apartment building, considered to be a major development in modern architecture. These new designs opened an economic door for contractors, engineers, architects, and investors, providing vast amounts of real estate space on minimal plots of land. Over the next fifteen years, many towers were built by Fazlur Rahman Khan and the " Second Chicago School ", including

8568-472: The upper rented to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven-stories buildings existed in provincial towns such as in 3rd century AD Hermopolis in Roman Egypt . The skylines of many important medieval cities had large numbers of high-rise urban towers, built by the wealthy for defense and status. The residential Towers of 12th century Bologna numbered between 80 and 100 at

8670-460: The walls on the lower floors on a tall building would be too thick to be practical. An early development in this area was Oriel Chambers in Liverpool , England, built in 1864. It was only five floors high. The Royal Academy of Arts states, "critics at the time were horrified by its 'large agglomerations of protruding plate glass bubbles'. In fact, it was a precursor to Modernist architecture, being

8772-463: The waterless urinals on April 5 after a compromise, which stated that the building's owners and city officials would monitor the performance of the waterless urinals, was reached. Piping that would allow water to flow to the urinals in case they needed to be converted was installed in the Comcast Center, which Liberty Property Trust says was always part of the building's plan. A week later, on April 13, Liberty Property Trust sold an 80-percent interest in

8874-604: The weight of the building. This development led to the "Chicago skeleton" form of construction. In addition to the steel frame, the Home Insurance Building also utilized fireproofing, elevators, and electrical wiring, key elements in most skyscrapers today. Burnham and Root 's 45 m (148 ft) Rand McNally Building in Chicago, 1889, was the first all-steel framed skyscraper, while Louis Sullivan 's 41 m (135 ft) Wainwright Building in St. Louis, Missouri, 1891,

8976-469: The winter garden. The screen is composed of 7.8 million, 4.66mm pitch pixels housed in 6,771 LED modules of the type used in the Barco NX-4 panel. The installation, designed and produced by Niles Creative Group, premiered on June 6, 2008, and runs eighteen hours each day. The content of the video includes panoramic views of Philadelphia historic sites, images of space, dancers, acrobats and actors moving around

9078-814: The world have more than 100 skyscrapers that are 150 m (492 ft) or taller: Hong Kong with 552 skyscrapers; Shenzhen , China with 373 skyscrapers; New York City , US with 314 skyscrapers; Dubai , UAE with 252 skyscrapers; Guangzhou , China with 188 skyscrapers; Shanghai , China with 183 skyscrapers; Tokyo , Japan with 168 skyscrapers; Kuala Lumpur , Malaysia with 156 skyscrapers; Wuhan , China with 149 skyscrapers; Chongqing , China, with 144 skyscrapers; Chicago , US, with 137 skyscrapers; Chengdu , China with 117 skyscrapers; Jakarta , Indonesia , with 112 skyscrapers; Bangkok , Thailand , with 111 skyscrapers, and Mumbai , India with 102. As of 2024, there are over 7 thousand skyscrapers over 150 m (492 ft) in height worldwide. The term "skyscraper"

9180-648: The world's tallest building for forty years. The first completed 417 m (1,368 ft) tall World Trade Center tower became the world's tallest building in 1972. However, it was overtaken by the Sears Tower (now Willis Tower ) in Chicago within two years. The 442 m (1,450 ft) tall Sears Tower stood as the world's tallest building for 24 years, from 1974 until 1998, until it was edged out by 452 m (1,483 ft) Petronas Twin Towers in Kuala Lumpur, which held

9282-432: The world's tallest building, New York took the lead by 1895 with the completion of the 103 m (338 ft) tall American Surety Building , leaving New York with the title of the world's tallest building for many years. Modern skyscrapers are built with steel or reinforced concrete frameworks and curtain walls of glass or polished stone . They use mechanical equipment such as water pumps and elevators . Since

9384-470: The world, although only partially iron framed, is The Flaxmill in Shrewsbury , England. Built in 1797, it is seen as the "grandfather of skyscrapers", since its fireproof combination of cast iron columns and cast iron beams developed into the modern steel frame that made modern skyscrapers possible. In 2013 funding was confirmed to convert the derelict building into offices. In 1857, Elisha Otis introduced

9486-650: The years immediately following World War II. Early examples include Edificio España (Spain) and Torre Breda (Italy). From the 1930s onward, skyscrapers began to appear in various cities in East and Southeast Asia as well as in Latin America . Finally, they also began to be constructed in cities in Africa , the Middle East , South Asia , and Oceania from the late 1950s. Skyscraper projects after World War II typically rejected

9588-413: Was designed by Daroff Design + DDI Architects and Gensler . Comcast's space is topped by a conference room floor with the executive offices on the four floors below it. Below that are more offices and then, on the 43rd and 44th floors, is Ralph's Cafe, a two-story cafeteria space named after the company founder Ralph J. Roberts . Below the cafe is the training center called "Comcast University". The rest of

9690-637: Was director of Philadelphia's development agency. Rendell dismissed the claims, saying "Every building owner in town was a contributor to me." Chances the bill would be passed ended in November 2004 when House Republicans in the Pennsylvania General Assembly decided not to bring the bill to a vote. Later that year, Governor Rendell released US$ 30 million from the Redevelopment Assistance Budget to Liberty Property Trust. Through

9792-611: Was first applied to buildings of steel-framed construction of at least 10 stories in the late 19th century, a result of public amazement at the tall buildings being built in major American cities like New York City , Philadelphia , Boston , Chicago , Detroit , and St. Louis . The first steel-frame skyscraper was the Home Insurance Building , originally 10 stories with a height of 42 m or 138 ft, in Chicago in 1885; two additional stories were added. Some point to Philadelphia's 10-story Jayne Building (1849–50) as

9894-723: Was held at night, featured a light show coordinated with a piece of music entitled "Elevation". The song was composed specifically for the event by Curtis Institute of Music graduate Steven Hackman and recorded by the Curtis Institute of Music Orchestra. The groundbreaking also featured Kodo , the Germantown High School drumline , and a 6-foot-tall (1.8 m) ice sculpture of the Comcast Center. While under construction, in March 2006, Liberty Property Trust negotiated with Philadelphia's Plumbers Union Local 690, which had issues with

9996-451: Was held in the building's future plaza, featured the raising of a steel beam to the skyscraper's highest point. The beam was signed by workers and guests and as it was raised, on account of tradition, an American flag and a tree sat on the beam. Also sitting on the beam was a statue of Philadelphia-founder William Penn . The statue was there to counteract the 1980s "curse" of Billy Penn , which prevented Philadelphia's sports teams from winning

10098-424: Was in 17th-century Edinburgh , Scotland, where a defensive city wall defined the boundaries of the city. Due to the restricted land area available for development, the houses increased in height instead. Buildings of 11 stories were common, and there are records of buildings as high as 14 stories. Many of the stone-built structures can still be seen today in the old town of Edinburgh. The oldest iron framed building in

10200-432: Was named after a popular table at the former Perrier and Scarduzio establishment Brasserie Perrier. Table 31 closed in 2013, amid a dispute among its owners, and was replaced by another upscale steakhouse, named "Chops". Philadelphia Inquirer architecture critic Inga Saffron described the Comcast Center as "a respectable work of architecture" that was "dignified in its stance on the grid, generous in its relationship to

10302-454: Was the concept of the "tube" structural system , including the "framed tube", "trussed tube", and "bundled tube". His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design. These systems allow greater economic efficiency, and also allow skyscrapers to take on various shapes, no longer needing to be rectangular and box-shaped. The first building to employ

10404-596: Was the first steel-framed building with soaring vertical bands to emphasize the height of the building and is therefore considered to be the first early skyscraper. In 1889, the Mole Antonelliana in Italy was 197 m (549 ft) tall. Most early skyscrapers emerged in the land-strapped areas of New York City and Chicago toward the end of the 19th century. A land boom in Melbourne , Australia between 1888 and 1891 spurred

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