Impressive Romanesque fortress

Impressive 11th-century Romanesque fortress. It houses the church of Santa María.

It was built in the late 11th century on the orders of King Sancho Ramírez I of Aragon, on the remains of an old Roman fortress. It is considered to be the most important Romanesque fortress in Spain. It has an irregular floor plan and a double wall with cylindrical towers. The 12th-century Romanesque church of Santa María is on the interior, and has three naves and a barrel vault. It has capitals decorated with Roman iconography. It was first a royal residence, and later an Augustinian monastery.