The present military architecture reflects the strategic importance that the region has always had in the national defence context.
Apart from the already mentioned Casters and Castles, a natural relevance is given to the coast defence Fortresses, by the grandness of the work and importance of the protectness of the national integrity, for example: in Paimogo, the one in the Berlengas Island called S. João Baptista and the imponent fortress of Peniche, that had a considered political importance in the 20th century. All these edifications are from the 17th century. Of a more recent provenience are the fortresses of Linha de Torres that in the beginning of the 19th century served efficiently in the defence of Lisbon during the French Invasions, outstanding the Fortress of S. Vicente in Torres Vedras for its state of preservation.