Castle of la Palma Monument · Sástago, Ribera Baja del Ebro, Zaragoza Image of Sástago, not of the place itself. Raised on the summit of a hill in Sástago, in the Ribera Baja del Ebro, this castle of Muslim origin from the 10th century watched over the river's meander and the passage towards Bajo Aragón; after the Christian conquest it was absorbed into the lordship of the Alagón family and lost its military function. Rectangular in plan and oriented north to south, the medieval walled precinct was protected by towers and a keep, with the gate on the north side; a chapel and other Baroque buildings were later raised inside it. Today much of it lies in ruins and only the main tower, of irregular masonry, still stands. Included in the Lista Roja del Patrimonio en Peligro, it is among the castles declared Bien de Interés Cultural (Spain's highest level of heritage protection) under the Law on Aragonese Cultural Heritage. siglo X Photo: Ecelan (CC BY-SA 4.0) What to see and do in Sástago