The skyscraper has a history extending back more than 120 years, but it entered a new phase of innovation and acceleration in the late 1960s. The Council on Tall Buildings and Urban Habitat was founded in 1969 to embrace and interpret the rapid changes taking place in the field of high-rise design and engineering. Throughout its history, CTBUH has highlighted best practice examples of tall buildings that represented a significant change in thinking or technique, by means of Journal case studies, conference proceedings, and since 2002, the annual Awards program.
The tall buildings captured here are selected on the same criteria, through the combined input of the CTBUH Research and Data team, CTBUH Leaders, and a call to the member constituency at large. Each represents a milestone in the development of the typology, tracking the development of the tall building from a predominantly commercial office tower with repetitive floor plates, to a “vertical city” with the mix of uses, variation in façade materials, and variety of interior and exterior spaces implied by the title. Across these examples, we see the arrival and departure of the distinct International and Post-Modern styles, as well as the overlapping parametricism and contextualism that dominates the contemporary scene. We see the transition from symbols of North American corporate power to broadcasting devices for the arrival of entire cities and countries on the global stage. The importance of environmental sustainability takes on as important a role as cultural and economic longevity. And, as some of these skyscrapers hit the half-century mark, we see them aging gracefully, into new functions, sometimes radically changing appearance and even height. From this, we learn that the development of the skyscraper typology is not a simple case of linear hand-offs from one generation to the next; rather, it is an interpolating dialogue that will continue to inform and inspire us for the next 50 years and beyond.
In addition to providing a generous public plaza at its base, due to its elliptical shape and deft space planning, 1 Bligh Street was Sydney's first CBD commercial office tower to incorporate blackwater recycling, reducing the demand on municipal potable water by 90 percent. It also contains Australia's largest green wall on the ground floor level; it was the first tall building in Australia to feature a double-skin glass façade with external louvers.
At the time of its completion, 4 Times Square was heralded as the greenest high-rise building in the world. Its notable features include environmentally friendly gas-fired absorption chillers, along with a high-performing insulating and shading curtain wall, which ensures that the building does not need to be actively heated or cooled for most of the year.
In helping to define a modern, open, and progressive image for one of the world’s oldest financial centers, 30 St Mary Axe set a benchmark in architectural quality for a new generation of tall buildings. Initially derided by critics for its unusual shape, it nevertheless became popular. As well as appearing on a stamp, the tower has been used extensively in the promotion of London through advertising, including on Olympic bid posters. The nickname “Gherkin” has now been trademarked by the owners.
Considered to be the first “post-modern” skyscraper in Chicago, the elegant sweeping curve of its green glass façade follows the bend in the Chicago River, mirroring the shimmering waters at certain hours. It is notable the design considerations taken when addressing to the Chicago street grid, river, and the adjacent skyline.
The headquarters building for AT&T in the heart of Manhattan, later to become the US headquarters of Sony, was a trail-blazing tour de force of post-modernism. Its peaked roof and broken pediment reminded citizens and critics of everything from a Chippendale dresser to an old-style cradle telephone. It paved the way for numerous other post-modern skyscrapers appearing on skylines around the world.
With its distinctive 45-degree roofline and its support by four massive 35-meter columns at the base, the Citicorp Center emerged as an icon for its generation. It was the first building in the US to feature a tuned mass damper (TMD). However, post-design tunnel tests showed the building, constructed using economical bolted joints, could collapse. Crews worked at night for three months, after the building was constructed and clad, welding steel plates over the building’s 200 bolted joints.
The John Hancock Center employed the first braced-tube structural system for a high-rise building, representing a bold early experiment in the mixed-use supertall typology, projecting scale and grandeur and honest visual expression, without embellishment. It introduced a new, recognizable vocabulary of structural expression that continues today. Its exterior bracing allowed the building to consume the same amount of steel as that of a conventional building half its height.
Among the most striking façades of any tall building, the operable, clamshell-like array enclosing the Al Bahar Towers represents a dramatic approach to resolving the issue of intense solar radiation in the desert climate. The façade’s moveable components are semi-transparent panels, which are combined in arrays much like umbrellas. Each array opens and closes in direct reaction to the sun’s position. While the system improves the comfort and light in the spaces inside, it also reduces the need for artificial lighting and overall cooling loads.
Among the final projects of Ludwig Mies van der Rohe, the AMA Plaza is one of the pinnacles of the International Style, showcasing rigorous tectonic discipline, and constructed on a challenging site over streets and rail lines adjacent to the Chicago River. Its 2013 retrofit preserved the travertine marble lobbies and added a luxury hotel to the lower third of the building, raising its public profile.
The Aqua Tower is designed to capture particular views that would otherwise be unattainable. A series of contours defined by outdoor terraces extends away from the face of the tower structure to provide views between neighboring buildings. The terraces inflect based on criteria such as the view, solar shading and size and type of dwelling. When viewed together, these unique terraces make the building appear to undulate, presenting a highly sculptural appearance that is rooted in function.
Two sail-shaped towers, connected by bridges supporting giant wind turbines, put the Bahraini capital on the world skyscraper map. This was the first large-scale integration of wind turbines with a tall building, making a strong, visible statement about the importance of incorporating natural sources of energy production into tall building design. The inspiration for the design came from regional vernacular “wind towers” and the vast sails of the traditional Arabian dhow.
With the Bank of America as its primary tenant, occupying six trading floors and 75% of its interior, the tower signals a significant shift in corporate America and in the real estate industry, acknowledging the higher value of healthy, productive workplaces. The building’s advanced technologies include a clean-burning, on-site, 5.0 MW cogeneration plant, which provides approximately 65% of the building’s annual electricity requirements and lowers daytime peak demand by 30%.
The Bank of China Tower used a sophisticated exterior bracing system, using the form of bamboo shoots—as symbols of strength, growth, and prosperity—for inspiration. The whole structure is supported by five steel columns at the corners of the building, with the triangular frameworks transferring the weight of the structure onto these five columns. This innovative composite structural system not only resists high-velocity winds, but also realized significant savings in construction time and materials.
The twin residential towers gained worldwide attention when completed, due to their supporting to 480 large trees, 250 small trees, 11,000 groundcover plants and 5,000 shrubs, which is equivalent to an entire hectare of forest cover. The foliage acts to improve air quality by filtering out dust and sequestering carbon, while also mitigating the urban heat island effect and reducing noise pollution, showcasing the potential of tall buildings to effect positive environmental change in cities.
The Burj Al Arab is regarded as one of the first key landmarks of modern Dubai. Inspired by the shape of a sailboat about to head into the Persian Gulf, the triangular building’s design began with an intent to create a recognizable landmark for the emerging city. Upon completion, Burj Al Arab was the world’s tallest hotel and included the world’s tallest atrium, which rises 182 meters through the interior of the building.
Burj Khalifa, the world’s current tallest building, has redefined what is possible in the design and engineering of supertall buildings. By combining cutting-edge technologies and cultural influences, the building serves as a global icon that is both a model for future urban centers and speaks to the global movement towards compact, livable urban areas. At the center of a new downtown neighborhood, Burj Khalifa’s mixed-use program focuses the area’s development density and provides direct connections to mass transit systems. Burj Khalifa’s architecture has embodied references to Islamic architecture and yet reflects the modern global community it is designed to serve.
CCTV’s twisting loop shape poses a truly three-dimensional experience, culminating in a 75-meter cantilever. Making extensive use of a continuous braced-tube structural system, the engineering forces at work are rendered visible on the façade through a web of triangulated diagrids that becomes denser in areas of greater stress, and looser in areas requiring less support. CCTV paved the way for future skyscrapers that would question the very idea of the tall building as a singular monolith.
Commerzbank Tower is recognized as one of the first high-rises in the world to incorporate a comprehensive ecological strategy, interspersing office zones with communal sky gardens throughout the building. The building relies substantially on natural lighting and ventilation, achieving 20 percent less energy consumption than was predicted by the original design. There has been a year-on-year reduction in energy consumption since 2000. Despite being more than 20 years old, Commerzbank Tower remains a benchmark for tall building sustainability even today.
The first skyscraper with internal reinforced-concrete diagrid columns, Doha Tower takes a cylindrical form for its efficiency in floor-to-window area and relative distances between offices and elevators, augmented by an off-center core. The cladding system is a reference to the traditional Islamic shading screen. The design for the system involved using a single geometric motif at several scales, overlaid at different densities along the façade. The overlays occur in response to the solar conditions of each elevation.
In sharp contrast to its classical base, intended for an unbuilt skyscraper from the 1930s, the angular, diagrid-supported Hearst Tower is immediately recognizable. The diagrid required 9,500 metric tons of structural steel—reportedly about 20% less than a conventional steel frame. Hearst Tower was the first skyscraper to break ground in New York City after the attacks of September 11, 2001.
The design of the HSBC Headquarters is much-emulated, as it achieved a unique harmony of public space, practical reconfigurability, and iconicity. The open-space needs of the bank led to the placement of elevators, stairways and building services at the ends of the office floors. The floors were suspended between the cores and pairs of steel masts located at the ends of the building. A mirrored sun scoop reflects natural daylight into the atrium, and through a glass ceiling to an open-air public plaza below.
As Hong Kong’s tallest building, the International Commerce Centre (ICC) houses some of the most prominent financial institutions in the world. It is routinely recognized as a paragon of good management, from a commercial, environmental, and community standpoint. The level of energy efficiency achieved by the ICC is unusual for a tall building, and significant investments have been made in improving energy performance over the years, through more than 50 advanced energy-saving measures.
When completed, this office tower became the tallest building in Asia, and held the title for seven years. The circular porthole-shaped windows are inspired by the nautical history of the city and the building’s site. It also formed a key node on the city’s growing skybridge network.
The Jin Mao Tower is an important building for Shanghai and China. Its setbacks and spire recall the skyscrapers of 1920s New York, while its stacked, stepping form resembles a pagoda, establishing it as a distinctly Chinese landmark. Its soaring interior atrium runs through the top third of the tower, providing a dramatic view from the hotel room corridor balconies.
Linked Hybrid presents one of the most advanced contemporary realizations of horizontally-linked tall building networks that have appeared in architectural discourse since the late 19th century. Conceived as a kind of intentional community that would be comprehensive and yet inviting to the greater city. The result is a multi-functional complex with eight skybridge links between nine towers. Each of the skybridges contains a different program, taking on the important social and commercial qualities of a high street literally, at 12 to 18 stories above the ground plane.
Taking inspiration from traditional Korean art forms in the design of the various interior program spaces, the sleek tapered form of Lotte World Tower stands out from Seoul’s rocky, mountainous topography. The tower is programmed with a great variety of functions, including retail, offices, a luxury hotel, and “officetels”, common in South Korean real estate, which offer studio-apartment-style accommodations for people who work in the building. The top 10 stories contain public entertainment facilities, including an observation deck and rooftop café.
MahaNakhon means “Great Metropolis” in Thai language. It integrates with the city through its organic form, by dissolving the mass as it moves between sky and ground. The dematerialization exercise returns a sense of the human scale to what would otherwise be an imposing structure. It is not short on theatrics, however—a glass-floored observation deck awaits visitors’ ascent to the summit.
Part of a massive regeneration of the Singapore waterfront, the Marina Bay Sands is now an indelible icon of the city-state. With three hotel towers supporting a massive “skypark”, topped with public recreation functions and a spectacular infinity pool, the project offers a gateway-like public asset that is truly connected to the network of pedestrian promenades around its namesake marina. The success of the project has inspired similar, and even larger multi-tower, horizontally-connected “mini-cities” in other cities.
A product of unique spatial constraints, the elliptical Mode Gakuen Cocoon Tower houses three different trade schools in one tower, in which three rectangular classroom areas rotate 120 degrees around the inner core. Student lounges are located between the classrooms, facing three directions. Each atrium lounge is three stories high and offers sweeping views of the surrounding cityscape. The tower played a large role in defining the “vertical campus” for the future.
This corporate headquarters, Saudi Arabia’s tallest building for 17 years, was one of the first tall buildings to adapt the specific vernacular techniques of local architecture in the Middle East. Office floors are clad with windows facing the courtyard, and solid walls of Roman travertine line the exterior, illuminating interior spaces with ambient sunlight, but eliminating heat gain from direct solar exposure.
One Central Park features vertical gardens and a heliostat affixed to a monumental cantilever extending 80 meters from the taller of the two constituent towers, delivering a distinctive and defining profile. The heliostat directs sunlight down into intermediate spaces between the towers that would otherwise be in shade. The plants’ shade reduces energy consumption for cooling, and their leaves trap carbon dioxide. In total, more than 5 kilometers of planters function like permanent shading shelves and reduce thermal impact in the apartments by up to 30 percent.
One World Trade Center recaptured the New York skyline, reasserted downtown Manhattan’s pre-eminence as a business center, and established a new civic icon for the US. The tower is a bold icon in the sky that acknowledges the adjacent 9/11 memorial. While the memorial, carved out of the earth, speaks of the past and of remembrance, One World Trade Center speaks about the future and hope as it rises upward in a faceted form filled with, and reflecting, light.
PARKROYAL on Pickering is a hotel with a contoured podium that responds to the street scale, drawing inspiration from terraformed landscapes, such as rice paddies, creating dramatic outdoor plazas and gardens that flow seamlessly into the interiors. Greenery from nearby Hong Lim Park is drawn up into the building in the form of planted valleys, gullies and waterfalls. The landscaping amounts to 215 percent of the site area, showing that, even as our cities become taller and denser, we do not have to lose our green spaces.
Using some of the most sophisticated technologies available, the Pearl River Tower was carefully shaped to use natural forces to maximize its energy efficiency. The tower’s sculpted body directs wind to a pair of openings at its mechanical floors, pushing turbines that generate energy for the building. East and west elevations are straight, while the north façade is convex. The concave south side of the building is dramatically sculpted to direct wind through the four openings, two at each mechanical level.
The twin towers of Petronas held the crown of “world’s tallest building” for six years, raising the profile of Kuala Lumpur, Malaysia and Asia itself as an innovative region for skyscraper development. Spanning the gap between the towers, at an elevation of some 170 meters, a two-level skybridge can also be used as a means of escape to the neighboring tower should one tower become unsafe in an emergency.
The design of the Post Turm opened up new possibilities for the work environment. From the onset of planning, the client expressed a strong desire to give all office staff direct access to outside air and natural light. The tower’s form consists of two, offset elliptical segments, each with an operable twin-shell façade, separated from each other by an atrium, through which hot air is exhausted through operable windows. It consumes 79% less energy than a comparable air-conditioned building.
Taking up the important mantle of becoming a San Francisco’s new tallest building, Salesforce Tower, interprets the role as a beacon. Its curtain walls rise past the top floor to form a transparent crown that appears to dissolve into the sky; at night it features 11,000 LED lights that project photographs of city life. It also features column-free bays and corners, which offer wide-open office spaces without any structural encumbrances. The tower is tightly integrated with a new neighboring transit center and park.
Shanghai Tower provides a vision of vertically-integrated space through a sinuous double-skin façade that contains numerous sky gardens, filled with vegetation and the potential for socializing. Upon opening in 2015, at 632 meters it became the tallest building in China, the second-tallest in the world, and one of only three “megatall” buildings of 600 meters or greater height in the world. Its façade and 14-story atria set into nine zones redefine the experience of being in a tall building, and deliver numerous environmental efficiencies.
The Shanghai World Financial Center is a symbol of commerce and culture that speaks to the city’s emergence as a global capital. Shaped by the intersection of two sweeping arcs and a square prism—shapes representing ancient Chinese symbols of heaven and earth, respectively—the tower’s tapering form supports programmatic efficiencies, from large floor plates at its base for offices to rectilinear floors near the top for hotel rooms. Its boldest feature, the 50-meter-wide portal carved through its upper levels relieves the enormous wind pressures on the building.
Holding the World’s Tallest Building title from 2004 to 2010, TAIPEI 101 has become a global icon and set a worldwide precedent for sustainable skyscraper development. The tower rises from its base in a series of eight-story modules that flare outward, evoking the form of a Chinese pagoda. It features energy-efficient luminaries, custom lighting controls, low-flow water fixtures, and a smart energy management and control system. The building has become a central component of New Year’s celebrations, including a dazzling fireworks display.
The design strategy of the Leadenhall Building centers around its lobby’s elevation above the ground plane, creating a generous public plaza, and its offset steel “megaframe” core, affording column-free floor plates of varying depths. It is the world’s tallest building to have used this strategy. With its distinctive wedge-shaped profile, which allows key view corridors to be maintained, it has been affectionately nicknamed the “Cheesegrater.”
One of the most-recognizable exemplars of the British High-Tech movement, the Lloyd’s Building is distinguished by its “inside-out” transposition of internal services - staircases, lifts, ductwork, electrical power conduits and water pipes—to the exterior, leaving an uncluttered space inside. Modular in plan, each floor can be altered by addition or removal of partitions and walls.
The tallest building in the UK reinvigorated a moribund district and capitalized on its excellent transport links, while providing a new icon for London. It also marked a number of firsts, including the first core to be built by top-down construction, which allowed the first 23 stories of the concrete core and much of the surrounding tower to be built before the basement had been fully excavated. This technique was a world first and saved four months on the complex program.
Torre Costanera, the tallest building in South America, derived its design comes from its close proximity to the Andes, and the need to distinguish the tower against this dramatic backdrop. The glass-clad tower has a slightly tapered, slender form that culminates in a sculptural, latticed crown. Beyond aesthetics, it is a 21st-century building technologically, including a highly advanced outrigger system to account for Santiago’s high level of seismic activity. The cooling tower draws its entire water supply from the adjacent San Carlos canal.
Torre Reforma is a dramatic departure from the existing high-rise architecture of Mexico City. Breaking from this mold has resulted in a versatile, column-free building that incorporates natural energy consumption-reducing elements and a structurally expressive exterior. The design provides a striking skyline figure, as well as quality multi-story communal space at height, and creative accommodation of a historic building at street level.
Tour First is a complete refurbishment of one of France’s first skyscrapers. The design retains the integrity of the original tower, while vastly improving the environmental performance, internal conditions and circulation. It reorganizes the entry levels of the building, reinvigorates the entrance hall and improves circulation. Seven sky gardens are created in strategic positions, providing informal meeting and breakout spaces. The original tower was extended, adding approximately 12 percent additional floor space. The project’s success has inspired even larger renovation and extension projects around the globe.
Upon completion, the distinctive Transamerica Pyramid became the tallest building in the US west of Chicago. It held the title of San Francisco’s tallest building for 46 years. In addition to recognizability, its tapering obelisk form was also selected for stability and as a means of curbing excessive shadows on the streets below.
The tallest building in Scandinavia, the Turning Torso was based on a sculpture by its architect, a white marble piece based on the form of a human in a twisting motion. It is widely considered the first “twisting” skyscraper, inspiring countless other designs. Its exoskeletal frame symbolically references the shipyard gantries of Malmö’s past, but points toward a progressive future, and has become a symbol of Sweden, featuring on a page of its citizens’ passports.
When built, U.S. Bank Tower was the tallest building in Los Angeles for 27 years. Its Art-Deco-via-Post-Modern design took cues from established local icons of the 1920s, including City Hall and the Central Library across the street. It is also notable for the public-realm improvements at its base, which is built into a hill. A cascading set of waterfalls and stairs descends around the perimeter.
Sears Tower was the tallest building in the world for 24 years, and set the standard for supertall skyscrapers worldwide. The designers developed both large office floors for Sears’ operation, but also a variety of smaller floors, which would be more suitable for tenants requiring less floor area. The result was a first-of-its-kind bundled-tube structure. It has proven to be a remarkably influential design typology, and has been used in many supertall buildings built since, including the Burj Khalifa.
1 The submissions ultimately accepted for publication were sent by: Rod Abid, CTBUH Skyscraper Center Editorial Board, Bangkok; Mir M. Ali, University of Illinois at Urbana-Champaign, Urbana, USA; Bridget Barnes, Skidmore Owings & Merrill, Chicago; Ana Bassat, b720 Arquitectura SL, Barcelona; Roland Bechmann, Werner Sobek AG, Stuttgart; Craig Blanchet, LeMessurier, Boston; Terri Boake, University of Waterloo, Toronto; Andrea Giachetti, University of Florence, Florence; Richard Henige, LeMessurier, Boston; Tailung Hung, Siemens, Hong Kong; Richard Lee, C.Y. Lee Architects & Planners, Taipei; Lucy Moloney, PTW Architects, Sydney; Christos Passas, Zaha Hadid Architects, London; Jonathan Schifman, Skidmore Owings & Merrill, New York City; Mohammed Shariq, JNTUH, Hyderabad; Hassan Siraj, Burjeel Engineering Consultancy, Abu Dhabi; Clare Swan, Ethos Urban, Kiama, Australia; Iping Yang, Taipei Financial Center Corp., Taipei.