Castell de Mequinensa is an intact palace-castle perched on a hilltop overlooking the strategic confluence of the Ebro, Segre, and Cinca rivers in Mequinenza, Aragon. Originally built by the lords of the Montcada family during the fourteenth and fifteenth centuries, this fortress commanded important territorial routes between Aragon and Catalonia. The castle underwent substantial restoration in 1959 by architect Adolf Florensa. Now private property belonging to the ENDESA Foundation, the castle maintains its historical integrity and can be visited by appointment on Tuesday mornings through prior arrangement with the municipality.