Temple of Mercury, Puy de Dôme

A Gallo-Roman temple built in the 2nd century AD atop the Puy de Dome volcano summit, replacing a smaller 1st-century temple that could not accommodate the many pilgrims. Dedicated to Mercury, the god syncretized with Celtic deity Lugus, it was constructed on a massive terrace with 60-meter sides using local trachyte stone, with decorative marble, Autun shales, and arkose capitals. Discovered in 1872 during observatory construction, excavations from 1873 to 1878 confirmed its function through artifact recovery including a Mercury statuette. Classified as a historic monument in 1889, the ruins underwent partial reconstruction from 2008 to 2014.