The road from Santa Cruz winds 7km up to the 10th-century Monasterio Viejo, tucked protectively under an overhanging lip of rock. A fire in 1675 led the monks to desert this original site and build the Monasterio Nuevo 1.5km further up the hill. Abandoned by the mid-19th century, these historic monasteries have since been rehabilitated and merit a visit by anyone interested in architecture, sculpture, history, scenery or wildlife.
The Monasterio Viejo, one of the most important monasteries of old Aragón, contains the tombs of Aragón's first three kings – Ramiro I (1036–64), Sancho Ramírez (1064–94) and Pedro I (1094–1104) – and two churches (the lower one Mozarabic, the upper one Romanesque). But its greatest highlight is the Romanesque cloister, with marvellous carved capitals depicting stories from Genesis and the life of Christ.
The Monasterio Nuevo is a larger, two-towered, brick complex, whose main church is now the Centro de Interpretación del Reino de Aragón, playing a 40-minute audiovisual about Aragonese history. Beside this, the Centro de Interpretación del Monasterio has been built over the archaeological remains of ruined parts of the monastery: it has Spanish-language panels on the monasteries' history and the kingdom of Aragón, plus a glass floor through which you look down on somewhat cheesy life-sized tableaux of monastic life.
Tickets for both monasteries are sold at the Monasterio Nuevo, and in peak periods (Semana Santa, July, August and a few holiday weekends) this is where you'll have to park. A free bus shuttles down to the Monasterio Viejo and back. Ticket prices depend on how many of the interpretation centres you wish to visit.