A trachyte temple for pilgrims at Puy de Dôme

The Temple of Mercury at Puy de Dôme was built in the 2nd century on a strong terrace at the summit of a lava dome. It replaced a 1st-century arkose temple on the same site, which was apparently too small to accommodate the many pilgrims who visited. The new structure was built with local trachyte, assembled in large blocks for the visible parts, and filled an area of around 3,600 m2.

The temple's design was a hybrid between Celtic and Mediterranean traditions. It included a cella as found in the fana of Celtic tradition, fronted by a Mediterranean pronaos. While the raw material was extracted near the Ceyssat pass, the decoration used other types of stone from more distant origins, including white and colored marbles for the pavements and arkose column capitals. Bronze was also used in the construction.

Coins discovered at the site indicate that the temple was still in use in the 4th and 5th centuries, though the structure could have been ruined by the 3rd century. Today, the remains are subject to harsh climatic conditions. A restoration project began in 2008 to preserve the ruins and help visitors better appreciate the scale and appearance of the temple in its original state.

This restoration has faced criticism from some archaeologists. Frédéric Trément, who excavated the site between 1999 and 2003, stated that the proposed reconstruction has the paradoxical consequence of making the ruins invisible behind an imposing and hideous Berlin Wall. Dominique Tardy similarly disapproved, noting that while the goal was to help visitors understand the site, the massive reconstruction might prevent them from understanding the processional system.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons