 The structure has been much restored and refurbished, notably by Émile Boeswildwald, architect to the French government in the 19th century, and a pupil of Eugène Viollet-le-Duc.The cathedral contains the relics of Saint Leo of Bayonne, a 9th-century Bishop of Bayonne and evangelizer of the Basque Country.The cathedral stands on the Pilgrimage Way of Santiago de Compostela and, as part of the Routes of Santiago de Compostela in France, has been added to the UNESCO World Heritage list in 1998.