This photo shows the original Twin Towers site. The 'smaller' towers behind the Twin Towers can be clearly identified in the previous photo. The Twin Towers had 110 floors and were over 1,360 feet (400 metres) tall. Fifty thousand people worked in the buildings. They were completed April 1973 but were the world's tallest buildings for only a short time, since the Sears Tower in Chicago was completed in May 1973. However, the towers were ranked as the fifth and sixth tallest buildings in the world at the time of their destruction on Sept. 11, 2001.