Castillo San Cristóbal

Castillo San Cristóbal is a fortress in San Juan, Puerto Rico. It was built by the Spanish to protect against land-based attacks on the city of San Juan. It is part of San Juan National Historic Site.

Castillo San Cristóbal is the largest fortification built by the Spanish in the New World. When it was finished in 1783, it covered about 27 acres of land and partly encircled the city of San Juan. Entry to the city was sealed by San Cristóbal's double gates. After close to a hundred years of relative peace in the area, part of the fortification was demolished in 1897 to help ease the flow of traffic in and out of the walled city.

Source: Wikipedia