On my last day in Puerto Rico, I explored Castillo San Cristobal, a fort built by the Spanish to protect San Juan from attack by land. It was built between 1634 and 1790, and then the U.S. added a few concrete additions during World War II. The fort is huge and has a series of tunnels. Some of these tunnels are huge, connecting the different levels and areas of the fort, and were designed to have defensive explosives. Some of the tunnels are really small, and you have to stoop to move through them. If you ever get a chance to visit, try to get one of the ranger guided tours of the tunnels. Those tours besides being very informative, let you go inside some of the really small tunnels in which you normally aren’t allowed.
View from top level
Old stone design
Upper level
Upper level looking into courtyard
Upper level artillery foundation
View from newer concrete WWII lookout
Entrance to small, normally inaccessible tunnel
Small, normally inaccessible tunnel
View from lower, exterior courtyard
Entrance to lower tunnel with symbol on top warning of explosives
Inside a tunnel
Dungeon entrance
Courtyard with view to city through window
Main courtyard
Entrance to the main tunnels
Soldiers’ quarters
Passageways in soldiers’ quarters
Exterior of fort