John Hancock Observatory

The observatory boasts the city's only open-air skyscraper deck, the product of a 1997 $2.5 million renovation that resulted in the replacement of nine-foot-tall plate glass windows with NASA-tested stainless-steel screens. From 1,000 feet up on the 94th floor, you can se up to 80 miles out and four states—you'll feel as if you're along for the ride as you watch airplanes whiz by. If that’s not compelling enough, a 2008 rehab gave the building a clean, sleek look and David Schwimmer–narrated self-guided tours that fill you in on the city’s history.