In 1992, the Tower of Venero in Castillo Siete Villas, Arnuero, was recognized a Cultural Heritage.

Martín Sánchez del Castillo ordered the 13th- and 14th-century fortification. It was a defensive construction in local feudal fights to expand their domains and vassals and a useful tool for feudal control.

Late medieval Venero Tower. It is 9 m square. Its mortared ashlar walls are 70 cm thick. The 10-meter-long elevation has four storeys.

Its interior resembles late medieval Cantabria towers.

Staircases connected all floors and could be removed in emergencies.

The south façade doorway features only a 1.40-metre-long arch. On the first story, a huge window with a semicircular arch led to a wooden scaffold supported by four ledges protruding from the wall. Two pointed-arched and two rectangular windows with inner overhangs exist on the first level. A crenellated cornice with arrow slits on two battlements on each side tops all façades.