Liberty Bell/Independence Hall, Philadelphia

Philadelphia's http://www.nps.gov/inde/"target="_blank">Independence National Historical Park holds the famous Liberty Bell and Independence Hall, where the Declaration of Independence and U.S. Constitution were signed. Both sites are free to visit, although you will need a timed entrance ticket for Independence Hall if you visit from March through December. Walk-up tickets are provided daily on a first-come, first-served basis, or you can reserve tickets up to a year in advance for a $1.50 per ticket fee. Be sure to wear comfortable walking shoes: The park spans a 20-block radius downtown, covering more than 55 acres. There's a variety of free guided tours available as well, including Franklin's Philadelphia, Slavery and the Underground Railroad, and Twilight Tours, among other options.

(Photo: J. Smith/Greater Philadelphia Tourism Marketing Corporation)