Standing at an awesome 452m (1,483 ft.) above street level, with 88 stories, the towers were the tallest buildings in the world from 1998 to 2004 (when Taipei 101 snatched the title). From the outside, the structures are designed with the kind of geometric patterns common to Islamic architecture, and on levels 41 and 42, the two towers are linked by a bridge. Visitors are permitted on the viewing deck on the bridge from 9am to 7pm every day except Mondays and public holidays. Also note that the viewing deck closes every Friday from 1 to 2:30pm. Otherwise, the building is accessible only if you are conducting business inside. Limited free tickets go fast, so line up early -- the ticket counter is on the lower ground (concourse) level of the Twin Towers.