Situated on the right bank of the Trancão River, near its mouth, at the top of the small hill called Monte Cintra, about 35 meters above sea level, the Forte de Sacavém, or Monte Cintra Redoubt, is a 19th century military building built within the fortification works in the capital, which formed the Lisbon Entrenched Camp, outlined after the end of the civil war. With a privileged strategic position, this stronghold supported the forts of Almada and São Julião da Barra, defending the river line up to Sacavém, as well as the Odivelas valley and the Monsanto mountain range.

It presents an irregular pentagonal plant (Vauban type), surrounded by a moat with counter escarpment and terrace, with a sharp slope towards the outside. This forms two overlapping land masses that cover a large part of the buildings, creating the illusion of a small hill, which makes it almost invisible when viewed from a lower altitude. The Forte de Sacavém follows the typology of fortifications facing the interior of the enclosure, making the interior embankment the center of all activities carried out in the redoubt, around which the three main building blocks were articulated.

The Forte de Sacavém currently holds the largest architectural archive in the country, with a documentary collection composed of more than 500 thousand drawings, 7 kilometers of shelves with administrative process, and 300 thousand photographs of buildings and national monuments.