Santa Ana Castle (Castro-Urdiales)

Few images sum up Castro-Urdiales better than its Santa Ana Castle, set on a rocky headland facing the Bay of Biscay. From the top you look out over the sea, the harbour and the town's rooftops, and one glance is enough to understand why this crag was chosen as a stronghold. Today it is regarded as one of the best-preserved castles in northern Spain, and its sturdy silhouette still defines the outline of the coast.

The fortress does not stand alone. It shares the small peninsula with the fortified 13th-century church of Santa María de la Asunción, the ruins of the earlier 12th-century church of San Pedro, and the hermitage of Santa Ana, built as a watchtower and linked to the castle by a bridge. The whole ensemble can be explored as a single historic setting, where the religious and the defensive go hand in hand.

The castle is striking for its pentagonal plan, reinforced at the corners by cylindrical towers fifteen metres high. Inside lies a rectangular enclosure and, within it, a hall covered by a barrel vault. Four of these cylinders actually serve as buttresses for the vault, while the fifth encloses a triangular space that juts out towards the town. Its walls, made of huge cyclopean stones bound with lime, have no openings whatsoever, so the castle could only be defended from the towers.

In 1853 the site took on a new life when a lighthouse was installed there, its machinery eventually taking over the chapel; hence it is often called the castle-lighthouse. In this area you can also make out another, lower crenellated defence. In the past, the castle and citadel were surrounded by a wall six to seven metres high, of which a small, badly deteriorated stretch still survives, complete with its original crenels and merlons.

One final detail for visitors: the entrance faces not the town but the sea, through a small doorway that shows just how much this fortress lived with its face turned towards the Bay of Biscay.