"Absorb Puerto Rican History Where It Was Made You can learn about Puerto Rico 's history by visiting ancient citadels, churches, and Taíno ceremonial sites. The island, considered the "Key to the Antilles" by the Spanish, was fought over in many wars; the 1539 El Morro in Old San Juan—the Caribbean’s largest fortress—played an important role in many of these conflicts. Hide in watchtowers overlooking the water, role-play in the dungeons, and examine the cannons used in battle. Other educational historical sites include the Church of San Juan, which holds the tomb of conquistador Juan Ponce de León, and the Catholic art museum Porta Coeli, in San Germán, which was built by Dominicans in the 17th century."