Fort of São João das Maias
Oeiras e São Julião da Barra, Paço de Arcos e Caxias, Portugal · built 1644
The Fort of São João das Maias, also known as the Fort of Oeiras, is located on the right bank of the River Tagus estuary, in the municipality of Oeiras in the Lisbon District of Portugal. It was constructed between 1644 and 1653. Until 2010 it had been allowed to fall into a state of advanced degradation but in that year it was restored.
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).