Castillo de San Marcos National Monument

There is no way families should leave this out of your St. Augustine itinerary. The impressive fort which dominates the water front of the Old City was built by the Spanish from 1672-1695 is the oldest stone fortress in the continental United States, Its walls are made from coquina, rock made from compressed seashells found along the coast. Make sure to make your way to the top of the fort for spectacular views of the Mantanzas River. Re-enactors and park rangers will tell you the fort's history and provide historic weaponry demonstrations that go off with a bang on a regular basis. Open daily from 8:45 a.m. to 5 p.m. Closed Dec. 25.