St. Augustine, Florida
St. Augustine isn't nicknamed "Ancient City" for nothing. Juan Ponce de Leon first explored the area in 1513 and claimed it for Spain. It was later turned over to Britain, then back to Spain, and finally ceded (with the rest of the Florida Territory) to the United States in 1819.
You can see much of that rich history infused into St. Augustine's architecture in places like Ft. Matanzas National Monument, Castillo de San Marcos National Monument, the oldest wooden schoolhouse in the country, the Hotel Ponce de Leon (once a regal hotel, now part of Flagler College and also a designated National Historic Landmark), and, of course, the Fountain of Youth Archaeological Park. (Folklore says that Ponce de Leon was searching for the elixir of life when he stumbled upon St. Augustine.)
St. Augustine is also home to the St. Augustine Alligator Farm Zoological Park. The park opened its doors in 1893 and now houses more than 20 species of crocodile as well as other reptiles, a bird collection, and many mammals.