The 5th battery from the RAC - "Regimento de Artilharia de Costa" (Coast Artillery Regiment), located in Raposeira, Trafaria, Portugal.
Now abandoned, this battery was one of the eight built to defend the Lisbon and Setúbal coast from enemy ships.
More info in: [link]
(sorry, only in Portuguese).
Sigma 10-20mm F4-5.6 EX DC
Hitech 85 ND 0.9 GRAD SE filter