Some 9km south of Aigle and connected by hourly train is the small town of Bex (pronounced bay), unremarkable but for the fact that it sits beside the only working salt mine in Switzerland, named Le Bouillet. All through the Middle Ages Switzerland had to rely on importing salt, mainly from Franche-Comté – an expensive business, not least because of the transportation costs. Then, in the fifteenth century, legend has it that a shepherd pasturing his flocks above Bex noticed that the animals preferred drinking from two particular springs. Tasting the water himself, he discovered that it was salty and this led to further investigation, principally by the Bernese authorities, who began to mine the hills around Bex. The mines have been worked ever since, and today a labyrinthine network of galleries burrows for some 50km beneath the mountains, still producing salt for domestic consumption.

You can visit some portions of the mines on guided tours (April–Oct daily every 90mins 9.45am–3.45pm; reservations essential on 024/463 03 30; Fr.17, cash only). Tours (available in English) last for over two hours, beginning with an audiovisual show and including a long underground narrow-gauge train ride and plenty of subterranean walking. There’s no public transport to the mine entrance. Irregular buses run from Bex station to the village of Les Dévens, twenty minutes’ walk away, or you can walk from Bex itself in about 45 minutes.