What is the highest tower in United state of America ?
Willis Tower, formerly named Sears Tower, is a 108-story, 1451-foot (442 m) skyscraper in Chicago, Illinois. At the time of its completion in 1974, it was the tallest/highest building in the world, surpassing the World Trade Center towers in New York. Currently, Willis Tower is the tallest / highest building in the United States and the fifth-tallest