Burj Khalifa (Arabic: برج خليفة, ""Khalifa Tower"", pronounced English /ˈbɜrdʒ kəˈliːfə/), known as Burj Dubai before its inauguration, is a megatall skyscraper in Dubai, United Arab Emirates. It is the tallest artificial structure in the world, standing at 829.8 m (2,722 ft).Construction of Burj Khalifa began in 2004, with the exterior completed in 2009. The primary structure is reinforced concrete. The building opened in 2010, as part of the new development called Downtown Dubai. It is designed to be the centerpiece of large-scale, mixed-use development. The decision to build the building is reportedly based on the government's decision to diversify from an oil-based economy, and for Dubai to gain international recognition. The building was named in honor of the ruler of Abu Dhabi and president of the United Arab Emirates, Khalifa bin Zayed Al Nahyan; Abu Dhabi and the UAE government lent Dubai money to pay its debts. The building broke numerous height records.Burj Khalifa was designed by Skidmore, Owings and Merrill (SOM), who also designed the Willis Tower and the One World Trade Center, with Hyder Consulting chosen to be the supervising engineer with NORR Group Consultants International Limited chosen to supervise the architecture of the project. The design of Burj Khalifa is derived from patterning systems embodied in Islamic architecture, incorporating cultural and historical elements particular to the region such as the spiral minaret. The Y-shaped plan is designed for residential and hotel usage. A buttressed core structural system is used to support the height of the building, and the cladding system is designed to withstand Dubai's summer temperatures. A total of 57 elevators and 8 escalators are installed, with the elevators having a capacity of 12 to 14 people per cabin. Critical reception to Burj Khalifa has been generally positive, and the building received many awards. However, the labor issues during construction have been controversial, since the building was built primarily by workers from South Asia and East Asia, who earned low wages and were reportedly housed in poor conditions.