The Burj Khalifa (previously known as Burj Dubai prior to inauguration) is a megatall skyscraper in Dubai, United Arab Emirates. Designed by the SOM architectural firm, it is the world's tallest structure, with a total height of 829.8 m (2,722 ft, or just over half a mile) and a roof height (excluding the antenna, but including a 242.6 m spire) of 828 m (2,717 ft). It has been the tallest building in the world since its complete inauguration in 2011, surpassing Taipei 101, which had held the record since 2004.
Construction of the Burj Khalifa began in 2004; the exterior was completed five years later. The primary structure is reinforced concrete. Some of the structural steel for the building was salvaged from the demolished Palace of the Republic in East Berlin. The building was opened in 2010 as part of a new development called Downtown Dubai. It was designed to be the centrepiece of large-scale, mixed-use development. The building became fully operational with the opening of its last major facility in 2011.
The building is named after the former president of the United Arab Emirates (UAE), Sheikh Khalifa bin Zayed Al Nahyan. The United Arab Emirates government provided Dubai with financial support as the developer, Emaar Properties, experienced financial problems during the Great Recession. Then-president of the United Arab Emirates, Khalifa bin Zayed, organised federal financial support. For his support, Mohammed bin Rashid, Ruler of Dubai, changed the name from "Burj Dubai" to "Burj Khalifa" during inauguration.
The design is derived from the Islamic architecture of the region, such as the Great Mosque of Samarra. The Y-shaped tripartite floor geometry is designed to optimise residential and hotel space. A buttressed central core and wings support the height of the building. Its central core houses all vertical transportation except egress stairs within each of the wings. The structure also features a cladding system which is designed to withstand Dubai's hot summer temperatures. The Burj Khalifa has 57 elevators and 8 escalators.
Construction began on 12 January 2004, with the exterior of the structure completed on 1 October 2009. The building officially opened on 4 January 2010 and is part of the 2 km2 (490 acres) Downtown Dubai development at the 'First Interchange' along Sheikh Zayed Road, near Dubai's main business district.
When Burj Khalifa opened in 2010, much of the building was still unfinished internally. The inauguration was effectively completed when the last major planned facility of Burj Khalifa became operational on 23 January 2011, making the tower fully functional.
The tower's architecture and engineering were performed by Skidmore, Owings & Merrill of Chicago, with Adrian Smith as chief architect, and Bill Baker as a chief structural engineer. The firm had designed the Sears Tower in Chicago, a previous record holder for the world's tallest building.
Hyder Consulting was supervising engineer and NORR Group Consultants supervised the architecture. The primary contractor was Samsung C&T of South Korea, together with the Belgian group BESIX and the local company Arabtec.
Numerous complaints concerned migrant workers from South Asia, the primary building labour force, who were paid low wages and sometimes had their passports confiscated.
Burj Khalifa was designed to be the centrepiece of a large-scale, mixed-use development to include 30,000 homes, nine hotels (including The Address Downtown Dubai), 3 hectares (7.4 acres) of parkland, at least 19 residential skyscrapers, the Dubai Mall, and the 12-hectare (30-acre) artificial Burj Khalifa Lake. The decision to build Burj Khalifa was reportedly based on the government's decision to diversify from an oil-based economy to one that is service and tourism based. According to officials, projects like Burj Khalifa needed to be built to garner more international recognition and hence investment. "He (Sheikh Mohammed bin Rashid Al Maktoum) wanted to put Dubai on the map with something really sensational," said Jacqui Josephson, a tourism and VIP delegations executive at Nakheel Properties.
The tower was known as Burj Dubai ("Dubai Tower") until its official opening in January 2010. It was renamed in honour of the ruler of Abu Dhabi, Khalifa bin Zayed Al Nahyan; Abu Dhabi and the federal government of UAE lent Dubai tens of billions of US dollars so that Dubai could pay its debts – Dubai borrowed at least $80 billion for construction projects. In the 2000s, Dubai started diversifying its economy but it suffered from the 2008 financial crisis and the Great Recession, leaving large-scale projects already in construction abandoned.
The Burj Khalifa set several world records, including:
Tallest existing structure: 829.8 m (2,722 ft) (previously KVLY-TV mast – 628.8 m or 2,063 ft)
Tallest structure ever built: 829.8 m (2,722 ft) (previously Warsaw radio mast – 646.38 m or 2,121 ft)
Tallest freestanding structure: 829.8 m (2,722 ft) (previously CN Tower – 553.3 m or 1,815 ft)
Tallest skyscraper (to top of spire): 828 m (2,717 ft) (previously Taipei 101 – 509.2 m or 1,671 ft)
Tallest skyscraper to top of antenna: 829.8 m (2,722 ft) (previously the Willis (formerly Sears) Tower – 527 m or 1,729 ft)
Building with most floors: 163 (previously World Trade Center – 110)