Fortress of Santa Cruz de Anhatomirim, Portuguese colonial fortress on Anhatomirim Island, Brazil

The Fortress of Santa Cruz de Anhatomirim is an 18th-century stone military complex on a small island off the coast of Santa Catarina, reachable only by water. It consists of a barracks building with twelve arcades, artillery platforms, cannon emplacements along the walls, and a commander's house facing the Atlantic.

The fortress was built in 1739 by Portuguese brigadier José da Silva Paes to defend the Santa Catarina coast against Spanish naval threats. It was part of a broader chain of coastal fortifications that Portugal established during a period of territorial rivalry in South America.

The Federal University of Santa Catarina turned the site into a museum where visitors can see colonial weapons, uniforms, and everyday objects from garrison life. The arcaded barracks give a clear sense of how ordinary soldiers lived in this remote outpost.

The island is accessible only by boat, with departures from both Florianópolis and Governador Celso Ramos throughout the year. The grounds have uneven stone surfaces and steps, so wear sturdy shoes before setting out.

The fortress plan is polygonal, not circular, as shown in the 1786 survey by ensign José Correia Rangel, which records later changes to its outline. In 1777 the fort was abandoned by its defenders and, surrounded by five Spanish ships on the afternoon of 24 February, was garrisoned by only two soldiers. During the Paraguayan War it served as a convalescent hospital and a military prison.