The castle of Santa Cruz Monument · Membribe de la Sierra, Guijuelo, Salamanca Image of Membribe de la Sierra, not of the place itself. The castle of Santa Cruz, or of Navagallega, is a medieval fortification near Navagallega, in the Salamancan municipality of Membribe de la Sierra, listed as a Bien de Interés Cultural (Spain's highest level of heritage protection). It is regarded as an early medieval castle built over an earlier Roman fortification; together with the nearby Peña del Rey, it formed a defensive complex rebuilt in the early 10th century by order of Ramiro II of León, on this frontier of the Tormes. Rectangular in plan, it stands on the rock of the Peñas de Santa Cruz, in the Sierra Menor; its walls are of rubblework and lime, with remains of granite ashlar on the north and east faces, and at its western end it preserves the remains of the access tower. Now in ruins, it is on the Red List of Endangered Heritage after part of its features were looted. Photo: 19Tarrestnom65 (CC BY-SA 4.0) What to see and do in Membribe de la Sierra