The oldest commissioned ship in the U.S. Navy, the USS Constitution, better known as “Old Ironsides,” sails past the Boston skyline during its annual Fourth of July turnaround cruise in Boston Harbor in 2005.

Among the 600 guests onboard the cruise in 2006 were 10 who had received their U.S. citizenship in a naturalization ceremony presided over by U.S. Citizenship and Immigration Services.

The city of Boston is the home of the Freedom Trail, one of America's first historic walking tours, which introduces visitors to Colonial/Revolutionary Boston. A red brick or painted line connects the 16 historic sites on the trail, covering America's colonial period in the 17th and 18th centuries. (© AP Images)