This building dates back to 1760 and was constructed to protect the port from constant pirate attacks.

It consists of tall and thick stone walls that surround Cerro de San Basilio. The construction features small windows from which splendid views of San Blas can be enjoyed.

Currently, it has been restored and converted into a community museum where the history of the place is discussed. In addition to protecting against pirates, it was the scene of important battles during the War of Independence and some battles during the U.S. invasion in 1847 also took place here.

The museum also displays archaeological artifacts and pieces from the ships that arrived at the port.