The organ at Notre-Dame de Valère cathedral in Sion dates back to the 15th century, making it the oldest playable organ in the world. Spared by fire and war, it still attracts enthusiasts from all over the world. Standing majestically on top of a hill, the Basilica of Notre-Dame de Valère, a former residence of canons, dominates the city of Sion, the capital of canton Valais, southwestern Switzerland. Here, history unfolds in a mystical and sacred geography. Built in the 12th century, Notre-Dame holds a treasure: the oldest playable organ in the world. This instrument, which dates back to the 1430s, owes its survival to what might be called a miracle. Restored and embellished over the years, like the basilica that houses it, it is the object of international curiosity. "If I say I'm from the Valais, people will say, 'Ah, Valère'," says Edmond Voeffray, organist at Notre-Dame and co-author of the guide published by Swiss History of Art Society last August under the title "Les orgues ...