Stone fort
On the rocks.
Filipo tardim — CC BY-SA 4.0 · Filipo tardim — CC BY-SA 4.0 · Marcus Guimarães from Nova Friburgo, Brazil — CC BY 2.0 · Marcus Guimarães from Nova Friburgo, Brazil — CC BY 2.0
The Fort of São Mateus stands on a small rocky islet at the north-east end of Praia do Forte, at the mouth of the Itajuru channel that links Araruama lagoon to the sea. Brazil's chief fortifications engineer, Francisco de Frias da Mesquita, designed it in 1617, and work began in 1618 to protect Cabo Frio's first settlement, after the governor of Rio de Janeiro judged the earlier fort too exposed. Visitors walk up to the small stone fort, whose top looks along the long beach, the channel and the sea, and it sometimes hosts exhibitions. It is one of the city's most visited sights, with nearly sixty thousand visitors in the first four months of 2026. Entry is free, daily from morning until about 17:00, though hours may vary in season.
On the rocks.
Lagoon to sea.
Below the fort.
Rocky islet at the north-east end of Praia do Forte, mouth of the Itajuru channel, Cabo Frio
No, entry is free daily from morning until about 17:00.
