Feel the Auvergne's smouldering terrain beneath your feet at this mined volcanic site, across the main road from amusement park Vulcania. In summer, at weekends and during school holidays, a motorised 'train' chugs for 3km along the scorched scarlet soil, weaving past boulders flung out of the belly of this ancient volcano. Year-round, the site is visitable on guided walks. Lemptégy's geological forces are further explained through a short 'dynamic 3D' film (spoiler: expect bumps and jolts). Allow 2¾ hours.