320 Chestnut St.
Philadelphia, PA 19106
This two-story, Georgian-style brick building in Old City was a crucial meeting place in the United States' early history. The First Continental Congress met here, along with many semi-secret societies. For these reasons Carpenters' Hall is a National Historic Landmark and worth checking out.
The original purpose of the building was as a meeting place for the Carpenters' Company, and it still serves that purpose from time to time. It is free and open to the public, attracting more than 150,000 tourists each year.