Castle of Almeida

The Castle-Fortress of Almeida owes its existence to the border: implanted 763 metres over the valley of the River Côa, seven kilometres from the Castela-Leão plateau, it guarded Portugal's frontier with Spain. Around an earlier medieval castle a Vaubanesque, star-shaped bastioned fortress was built in the 17th and 18th centuries, and the whole is classified as a National Monument.

The fortress forms a twelve-pointed star on an irregular hexagonal plan: six uneven bastions linked by curtain walls over a perimeter of a mile and a half, with six triangular ravelins, a moat and a covered way. Cylindrical watchtowers with domed roofs stand at the angled corners of the northern ravelins, whose platforms were ramped for cannon and mortar placements. As late as 1661 the square was still not totally encircled and had no moat.

In the Siege of Almeida, Spanish forces under the Count of Aranda led a major offensive to take control of Portugal; the fortress was garrisoned by the Spanish and held despite set-backs, remaining the only major fortress still in Spanish hands by the end of the war before troops of the Alliance retook it. In 1764 the Count of Lippe re-examined the batteries. The famous 1810 explosion had its seat in the magazine of the cathedral adjacent to the castle, not the castle itself.