The oldest entrance to Aragon through the Pyrenees was the Roman road that crossed the Palo pass and went down Echo Valley, where the Carolingian monastery of Siresa was built. The important Romanesque church has been conserved and has a single nave and an apse. Inside there are important retables from the 13th century through the 15th century aswell as an interesting Gothic chalice.
Siresa Monastery was the spiritual centre of the primitive Realm. That road, as well as the parallel one through Anso Valley, goes through beautiful spots such as Zurita or la Selva de Oza and picturesque villages like Anso and Echo.