Castillo San Cristóbal. This is the view through one of the many arched windows in Castillo San Cristóbal, a beautiful 16th century fort in San Juan, Puerto Rico. The fort has been the center of many battles, seeing action against the English (multiple times!), Dutch, and the Americans. All this action led to a continuous improvement in the island’s defenses, with the main construction of Castillo San Cristóbal occurring in the 18th century. The Spanish-American war resulted in Puerto Rico becoming a US Territory at the end of the 19th century as part of the Treaty of Paris. Today the fort is finally peaceful and filled with a wonderful light spilling in though the stone arches.