After Seven World Trade Center was built in the 1980s, the World Trade Center complex had a total of seven buildings; however, the most notable ones were the main Twin Towers built in the 1970s—One World Trade Center was the North Tower, and Two World Trade Center was the South Tower. Each tower was over 1,350 feet (410 m) high, and occupied about 1 acre (0.40 ha) of the total 16 acres (6.5 ha) 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 response was, "I didn't want to lose the human scale.
When completed in 1972, One World Trade Center became the tallest building in the world for two years, surpassing the Empire State Building, which had held the record for 40 years. The North Tower was 1,368 feet (417 m) tall, and in 1978, a telecommunications antenna was added to the top of the roof; by itself, the antenna was 360 feet (110 m) tall. With the 360-foot (110 m)-tall antenna, the highest point of the North Tower reached 1,728 ft (527 m). The tower held its record for a brief period of time; Chicago's Sears Tower, finished in May 1973, was 1,450 feet (440 m) at the rooftop. At 110 floors, the World Trade Center towers had morefloors than any other building at that time. This number was not surpassed until the construction of the Burj Khalifa (163 floors), which opened in 2010.