The tower is the only remaining part of the old Benedictine monastery of San Cipriano de Cálogo, founded by San Fructuoso in the 7th century. The monastery was destroyed by Norman raids in the 9th and 10th centuries.
With a square base, it is made up of granite ashlars and on top there is part of a belfry with two semicircular arches in which there would be as many bells. Remains of an external staircase are also preserved, from which the bell tower would be accessed.
The tower is located in the highest part of the land, it does not have any type of decorative element and it was separated from the rest of the buildings, so everything seems to indicate that it was a defensive building built to give notice of the presence of invaders who had arrived by sea. In this way, it would form part of a more complex defensive system in which the different existing towers and fortresses along the coast would be integrated, culminating in the fortress and Torres de Oeste.
A document dating from 884 has recently been located in which a donation to the monastery is collected and in which express mention is made of the pilgrims to Santiago de Compostela, being the oldest reference, to date, of the Camino de Santiago in the Shire.