The municipality of Arce is crossed from north to south by the rivers Iratí and Urrobi. The Iratí valley comes down from the Pyrenees by Aezkoa and Oroz-Betelu while the Urrobi valley comes down from Burguete to flow into the Iratí at Itoiz.

In addition to the landscape appearance, Arce Valley has enough monumental elements to deserve a careful visit. The most important is the beautiful church of Santa Maria de Arce, one of the best examples of rural Romanesque. Visiting the church of Nagore is also a must, with interesting Romanesque sculpture and painting, especially the altarpiece presided over by the Gothic sculpture of Our Lady of Nagore.

We want to mention also that in this territory there are precious samples of noble palaces, some of them so old that were built with defensive towers. The main examples are the medieval fortified tower of Ayanz, the tower of Liberri and, of course, the tower of Uriz.