Visitors explore the walls and forts encircling Old San Juan but are often oblivious to other fortifications built by the Spaniards. In 1609, El Boquerón was constructed at the east end of the islet near the mouth of today’s Condado Lagoon. The four cannon defense battery was destroyed by privateers in the late 16th century. When the half-acre fortress was rebuilt, it was named Fortin de San Gerónimo de Boquerón. In 1797, San Gerónimo and the adjacent Fort of San Antonio were relentlessly bombarded by the British. Despite being grossly outnumbered and suffering crippling damage to their fort, the defenders repelled the attack. The citadel was rebuilt a couple years later and became a military post. This National Register of Historic Places property is now attached to the Caribe Hilton Hotel. Unfortunately, the historic site is closed because of its dilapidated condition.