Peñacastillo, Summit in Santander, Spain.

Peñacastillo is a mountain next to the village that rises 139 meters above sea level with steep slopes on its sides. The southeastern side shows limestone formations, while the northwestern part is covered with holm oaks and eucalyptus trees.

The mountain takes its name from ruins at the highest point, probably of a castle. It was formerly called Peña del Castillo. The church of Peñacastillo stands at 68 metres above sea level, near the summit.

The church near the summit is an important place for the local community and shapes how people view this location. It shows the religious meaning of the site for those who live in the surrounding area.

The mountain is best explored on foot starting from the base while being mindful of the steep slopes. An underground water reservoir located on the western side is a notable feature of the site.

The summit holds ruins, probably of a castle, which likely gave the mountain its name; it was formerly called Peña del Castillo. Between 2008 and 2009 a half-buried circular water tank holding 8,800 cubic metres was built west of the top to supply the surrounding population.