The Fort of Archeira was designated Military Work No.
128 of the 152 separate works carried out on the Lines.
It was on the first of the three Lines of Torres Vedras, to the southeast of the town of Torres Vedras and northeast of Monte Agraço, where the French were repelled.
 Designed for a garrison of 500 soldiers, Archeira had six 12-calibre guns.
Like all of the forts it was surrounded by a ditch, or dry moat.
Built at an altitude of 345 metres and following an irregular polygonal plan, it was the largest fortification of the Serra da Caduceira and was designed for a garrison of 500 soldiers.
This stronghold, together with the Feiteira (No.
129) and Fort of Catefica (No.
130), both to the north, defended the vulnerable Runa and Ribaldeira river valleys, under the command of Baron Christian Adolph Friedrich von Eben and General Brent Spencer, who was on two occasions Wellington's second-in-command.

The fort was one of the Lines of Torres Vedras signal stations.
Using an optical telegraph signalling system, it could communicate with the Fort of Alqueidão to the southeast and to both the Fort of São Vicente to the north of Torres Vedras and the Atlantic coast.
The Fort of Archeira was designated Military Work No. 128 of the 152 separate works carried out on the Lines. It was on the first of the three Lines of Torres Vedras, to the southeast of the town of Torres Vedras and northeast of Monte Agraço, where the French were repelled.  Designed for a garrison of 500 soldiers, Archeira had six 12-calibre guns. Like all of the forts it was surrounded by a ditch, or dry moat. Built at an altitude of 345 metres and following an irregular polygonal plan, it was the largest fortification of the Serra da Caduceira and was designed for a garrison of 500 soldiers. This stronghold, together with the Feiteira (No. 129) and Fort of Catefica (No. 130), both to the north, defended the vulnerable Runa and Ribaldeira river valleys, under the command of Baron Christian Adolph Friedrich von Eben and General Brent Spencer, who was on two occasions Wellington's second-in-command.
The fort was one of the Lines of Torres Vedras signal stations. Using an optical telegraph signalling system, it could communicate with the Fort of Alqueidão to the southeast and to both the Fort of São Vicente to the north of Torres Vedras and the Atlantic coast.
Fort of Archeira