The 80 dormant volcanoes of the Chaîne des Puys, located deep in France's central Auvergne region, are a geological wonder listed as a UNESCO World Heritage site. The green slopes attract hundreds of thousands of tourists each year, unfazed by the magma still bubbling 50 kilometres down. The rich volcanic soil also delights Auvergne's cows, whose milk is entirely devoted to the production of Saint-Nectaire cheese. Meanwhile, the petrified lava is turned into a stone that's been worked by local craftsmen for centuries.