how tall were the twin towers in floors
World Trade Center (1973–2001) When completed in 1972, 1 World Trade Center became the tallest building in the world for two years, surpassing the Empire State Building after a 40-year reign. The North Tower stood 1,368 feet (417 m) tall and featured a telecommunications antenna or mast that was added at the top of the roof in 1978 and stood 362 feet (110 m) tall. With the 362-foot (110 m)-tall antenna/mast, the highest point of the North Tower reached 1,730 feet (530 m).[91] Chicago's Sears Tower, finished in May 1973, reached 1,450 feet (440 m) at the rooftop.[93] Throughout their existence, the WTC towers had more floors (at 110) than any other building.[91] This number was not surpassed until the advent of the Burj Khalifa, which opened in 2010.[94][95] Each tower had a total mass of around 500,000 tons.[96]
Willis Tower As Sears continued to offer optimistic projections for growth, the tower's proposed floor count rapidly increased into the low hundreds, surpassing the height of New York's unfinished World Trade Center to become the world's tallest building. The height was restricted by a limit imposed by the Federal Aviation Administration (FAA) to protect air traffic. The financing of the tower was provided by the Sears company. It was topped with two antennas to permit local television and radio broadcasts. Sears and the City of Chicago approved the design, and the first steel was put in place in April 1971. The structure was completed in May 1973. The construction cost about US$150 million at the time,[18] equivalent to $830 million in 2018.[19] By comparison, Taipei 101, built in 2004 in Taiwan, cost around the equivalent of US$2.21 billion in 2018 dollars.[20]