Fort St. John is considered one of the most impressive monumental buildings Dubrovnik. Fort St. John also called Port Tower and Mulo. Strengthening is located in the south-eastern part of the Old Town of Dubrovnik and is part of a complex of fortifications of the city.

For centuries this was the main attraction of Dubrovnik protected from the sea by enemy ships and pirates. The walls of the fortress from the port of flat and steep, and from the sea - rounded and sloping.

Fortification on the site of the present fort was first built in the mid 14th century, the first fort is part of the fortress of St. John. Its present appearance gained fortress in the 16th century, when, in the course of reconstruction and rebuilding were merged two old forts and bastions.

Today, Fort St. John is a cultural and historical landmark. On the territory of the fortress are the Maritime Museum and Aquarium, which are very popular among tourists.

The aquarium is located on the first floor of the fort. There you can get acquainted with the marine fauna of the Adriatic Sea. The second and third floors are occupied by the Maritime Museum, which opened in 1872. In the Maritime Museum you can learn about the history of shipbuilding, shipping and maritime trade.