The 200-mile Ligne de Cévennes, which travels northwards through the Massif Central to France's volcanic heart - Clermont Ferrand and the spectacular Puy De Dome. The route takes travellers across three incredible historic viaducts, plunges deep underground to explore the area's hidden wildlife and traverses through several impressive valleys. The route winds through one of the world's most spectacular national parks, before reaching its final destination, a collection of 80 dormant volcanoes.

• Bill Nighy