In 1080, the viscount Centule V, Viscount of Béarn built the new city of "Oloron" (medieval version of the Roman name Iluro) on the opposite side of the river from the diocese center. Centulle V restored the Roman walls and founded the strong city of Oloron that was to be used as a base to retake the Aragon held by the Maures. The Oloron Cathedral was built at the beginning of the 12th century.