The historic site of San Juan, located on the northeast coast of Puerto Rico, was built in 1511 during the Spanish colonial rule, as a military fortification protecting the West Indies and the Spanish Empire, including fortifications, outlying positions, ammunition depots, city walls, moats, etc. The expansion and reinforcement of the following centuries served to prevent foreign aggression. In the 1898 American-Western War, the United States defeated Spain and since then Puerto Rico has belonged to the United States.