Castle of la Coracera Monument · San Martín de Valdeiglesias, Sierra Oeste, Madrid A 15th-century fortress built at the order of Don Álvaro de Luna as a residence and hunting lodge, with a pentagonal keep and a barbican some four metres thick; declared a Bien de Interés Cultural (Spain's highest level of heritage protection) in 1985, it lodged Isabel la Católica in 1468. Photo: Dirección General de Turismo. Consejería de Economía e Innovación Tecnológica. Comunidad de Madrid (CC BY 3.0 es) What to see and do in San Martín de Valdeiglesias