List of tallest buildings
The international non-profit organization Council on Tall Buildings and Urban Habitat (CTBUH) was formed in 1969 and announces the title of "The World's Tallest Building" and sets the standards by which buildings are measured. It maintains a list of the 100 tallest completed buildings in the world. The organization currently ranks Burj Khalifa in Dubai as the tallest at . The CTBUH only recognizes buildings that are complete however, and some buildings included within the lists in this article are not considered finished by the CTBUH.
World Trade Center (1973–2001)
One World Trade Center and Two World Trade Center, commonly the Twin Towers, the idea of which was brought up by Minoru Yamasaki, were designed as framed tube structures, which provided tenants with open floor plans, uninterrupted by columns or walls. They were the main buildings of the World Trade Center. The North Tower (One World Trade Center), the tallest building in the world at by the time of its completion, began construction in 1966 with the South Tower (2 World Trade Center); extensive use of prefabricated components helped to speed up the construction process, and the first tenants moved into the North Tower in December 1970, while it was still under construction. When completed in 1973, the South Tower, Two World Trade Center (the South Tower) became the second tallest building in the world at ; the South Tower's rooftop observation deck was high and its indoor observation deck was high. Each tower stood over high, and occupied about of the total of the site's land. During a press conference in 1973, Yamasaki was asked, "Why two 110-story buildings? Why not one 220-story building?" His tongue-in-cheek response was: "I didn't want to lose the human scale."