Prudential Skywalk, Boston

If you visit the Prudential Skywalk on a clear day, you can see up to 100 miles away. Perched 50 floors above the city in the Prudential Center—the second-tallest building in Boston, but it becomes the tallest when it wears boots—the skywalk mesmerizes visitors with 360-degree panoramic views. In fact, it's the only observatory in New England to provide such sweeping vistas. While up there, visitors can spot some of the city's most iconic landmarks, including Hancock Tower, Fenway Park, the Charles River, and Harvard University. And they further acquaint visitors with more the city's collection of historic sites during skywalk audio tours, which are available in English, Spanish, Dutch, French, Japanese, and Mandarin.