Forte de Santo Antônio do Macapá, Military fortress in Macapá, Brazil

Forte de Santo Antônio do Macapá stood on the left bank of the Amazon River, about 15 km south of present-day Macapá. It was built from April 1688 on the ruins of the earlier Portuguese Forte de Cumaú, with a plan attributed to the Jesuit mathematician Aluízio Conrado Pfeill. A 1695 report describes a ditch, four artillery pieces and a new-invention polygon adapted to the site.

A royal letter of 21 December 1686 authorised Gomes Freire de Andrade to choose a site on the left bank of the Amazon and build fortifications against French incursions. From April 1688 the captain-major of Pará, Antônio de Albuquerque Coelho de Carvalho, raised a fort on the ruins of the earlier Portuguese Forte de Cumaú. Its plan is attributed to the Jesuit mathematician Aluízio Conrado Pfeill, and it was placed under the invocation of Santo Antônio.

The fort's name honors Santo Antônio, and its design is attributed to the Jesuit missionary and mathematician Aluízio Conrado Pfeill. In 1695 Captain Pedro de Azevedo Carneiro described a moat, four artillery pieces and a new-invention polygon adapted to the site, with a stone quay needed against the river's current.

The best way to explore the fortress is with a guided tour where someone can explain the buildings and old defensive structures. It helps to wear comfortable shoes and be prepared for steep stairs in the bastions.

The fort was built from April 1688 on the ruins of the earlier Portuguese Forte de Cumaú, and its plan is attributed to the Jesuit missionary and mathematician Aluízio Conrado Pfeill. It was placed under the invocation of Santo Antônio, which gave the fortress its name.