The office and residence of the governor of Puerto Rico is the oldest executive mansion in continuous use in the Western Hemisphere, and it has served as the island’s seat of government for more than 3 centuries. Its history goes back even further than that to 1533, when construction began on a fortress to protect San Juan’s Spanish settlers during raids by Carib tribesmen and pirates. The original medieval towers remain, but as the edifice was subsequently enlarged into a palace, other modes of architecture and ornamentation were also incorporated, including baroque, Gothic, neoclassical, and Arabian. La Fortaleza has been designated a national historic site by the U.S. government. Proper attire is required (informal okay).