Visitor Center, Charlestown Navy Yard; (617) 242-5601
Take a free 45-minute tour of the docks, the rope walk, and the several historic ships moored here, all sponsored by the National Park Service. The visitor center is located next to the U.S.S. Constitution. Tours are given Wednesdays through Sundays at 11 a.m. and 1 rm. mid-June through early September. You can also walk around and even onto the ships on your own.