Its construction began in the 13th century and was completed during the 14th and 15th centuries. It is in an excellent state of preservation. Its walls are surrounded by a moat over which a drawbridge is lowered. The building was constructed in a polygonal design with four towers and an arms courtyard. Its walls, almost two metres thick, withstood numerous attacks during the Irmandiñas (Brotherhoods) Wars. It was the object of fierce disputes between the Archbishop of Compostela and the Moscoso family, two of the greatest powers in Medieval Galicia. For centuries it was the residence of the Counts of Altamira, until it was sold to the Martelo family. Finally it was passed into the hands of the A Coruña Provincial Government, which restored it and put it to public use.
In its interior we can visit a very interesting ethnographic museum, which contains examples of the craft specialities of the region, from stonework to baskets, as well as lace, ceramics, clogs and linen items, amongst others.