Willis Tower is Chicago's tallest building (and one of the world's loftiest). Breathe deeply during the ear-popping, 70-second elevator ride to the 103rd-floor Skydeck, then stride to one of the glass-enclosed ledges that jut out in midair for a knee-buckling perspective straight down some 1400ft.

　　A bit of history: it was the Sears Tower from its completion in 1973 until insurance broker Willis Group Holdings bought the naming rights in 2009. The building held the title of world's tallest building for almost a quarter century, surpassed by NYC's One World Trade Center in 2013.

　　Step out onto the glass-floor at the Willis Tower Skydeck © Julien Hautcoeur / Shutterstock

Tickets and other information

　　The entrance is on Jackson Blvd. Even with pre-booking, lines can take up to an hour on busy days (peak times are in summer, between 11am and 4pm Friday through Sunday, although some say sunset is the best time to visit).