In 1931, construction workers added the final nail to the Empire State Building in New York. At 1,250 feet high, it was the tallest building in the world, and remained so until the 110-story north tower of the World Trade Center finalized in 1972.
Then came Chicago's Sears (now Willis) Tower, followed by the Petronas Twin Towers in Kuala Lumpur and the Taipei 101 in Taiwan. In 2010, Dubai completed construction on the massive, 2,722-foot-high Burj Khalifa.
Image: WIKIMEDIA COMMONS JIM TRODEL
To read the original article: Underground Cities: The Next Frontier Might Be Underneath Your Feet
