Saint John's Fortress

Saint John's Fortress is a limestone structure in Dubrovnik's old harbor built with round walls facing the sea on a sloped base. The harbor side features vertical stone surfaces and contains a Maritime Museum, an aquarium, and studios operating inside.

Construction began in 1346 and continued through multiple phases until 1557, when two earlier forts merged into the present structure. This consolidation significantly strengthened the city's defense against threats from the sea.

The Maritime Museum inside displays seafaring history through ship models and tools used by medieval traders. The collections show how this harbor supported the city's role as a major Mediterranean trading center.

Visitors should know that the Maritime Museum, aquarium, and art spaces require separate entrance tickets and operate independently. Plan several hours if you want to see everything inside.

Stone vaults inside the fortress now house an aquarium where visitors can observe various species from the Adriatic. This unexpected use of historic space creates an interesting connection between the fort's past defense purpose and today's conservation effort.