Fortress of Santo Antônio de Ratones, Fortress on Ratones Grande island, Florianópolis, Brazil

The Fortress of Santo Antônio de Ratones is a military structure on Raton Grande island that consists of multiple stone and brick buildings arranged around a central compound. The site includes a commander's residence, barracks for troops, and various support structures built into the granite landscape.

It was built in 1740 as part of the Portuguese military expansion along the Santa Catarina coast. The fortress was one of three fortifications designed to defend the bay of Florianópolis against attacks from the sea.

The Quartel da Tropa hosts the photo exhibition "Fortaleza de Santo Antônio - Retrospectiva". On the island, a trail through Atlantic Forest and marine environments is used for ecological tourism and environmental education, and a photovoltaic station with solar panels was installed for teaching purposes. A mussel-farming project, a "sea farm", also operates here.

To visit the site, travelers take a boat from several points in Florianópolis and should plan for several hours to explore it properly. The trip works best on calm weather days when seas are manageable.

A Whitworth cannon with a hexagonal bore still stands at the fortress, a reminder of the 1893 Federalist Revolution when rebels occupied the site and installed two rifled cannons. The gun points toward the old harbor it once defended.