Fuerte San Lorenzo

Lonely Planet review

The Fuerte San Lorenzo was built in 1595, by order of Felipe II of Spain, to fortify the Río Chagres and the trade route to the city of Panamá. Despite its violent history, which includes constant pirate attack (and occupation by Sir Francis Drake himself), much of San Lorenzo is well preserved, including the moat, the cannons and the arched rooms.

Together with Portobelo, Fuerte San Lorenzo was declared a Unesco World Heritage Site in 1980. Like its contemporary fortresses at Portobelo, San Lorenzo was constructed of blocks of cut coral, and armed to the teeth with rows upon rows of cannons. If you inspect the cannons closely, you'll notice that some of them are actually British-made - a legacy of occupation by British pirates in the 17th century.