Organ of Basilica of Valère. It is generally agreed upon that the world's oldest playable pipe organ is located in the Basilica of Valère in Sion, Switzerland.Built around 1435, most of the case is original, but only 12 pipes are original, as the rest have been replaced during restorations. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.