El Morro, Puerto Rico < change city >

"Castillo San Felipe del Morro El Morro was initially fortified in 1539 and completed in 1589. Rising 140 feet above the sea, its 18-foot-thick wall proved a formidable defense. It fell only once, in 1538, to a land assault by the Earl of Cumberland's forces. The fort is a maze of tunnels, dungeons, barracks, outposts and ramps. Many restorations and expansions contributed to the imposing structure it is today. The area was designated a National Historic Site in February, 1949 with 74 total acres. Tours, orientation, and video presentation are available in English and Spanish. Open daily 9am-5pm. Free admission"