The GR 42 is a spectacular 450 km long-haul path winding from the rugged heights of the Massif Central to the wild wetlands of the Camargue. Starting in Saint‑Étienne, an emblem of 19ᵉ-century industry, you immediately enter the Pilat Regional Nature Park, where oak and conifer forests, as well as alpine flora like arnica and martagon lilies, paint a vivid ecological tapestry.