Idrija sits at the bottom of a narrow, steep-sided valley in western Slovenia, and for about five hundred years the town made a living from the red mineral cinnabar, the ore of mercury. The mine at Idrija was one of the largest mercury mines in Europe, second only to Almadén in Spain, and the two sites share UNESCO World Heritage status. The Kamšt is the best monument to that history: a huge wooden waterwheel, more than thirteen metres across, built in the late eighteenth century to drive pumps that kept the mine from flooding.
The wheel is fed by the Rake, a long channel carrying water from the surrounding hills to the town, an engineering feat of its time that tells you how seriously Idrija's miners took the problem of water underground. The mine's tunnels are open to visitors with a guide, and the town museum, in a castle above the centre, adds the stories of miners' families, mercury, and the lace-making that grew up alongside the mine. Idrija lace is still made, and the town celebrates it every June with a festival. For food, try žlikrofi, small potato dumplings that are protected as a local speciality, usually served with a meat sauce or on their own with a little bacon.
The roads into Idrija are what make the ride. From Logatec and Vrhnika you climb through forest and drop into the Idrijca valley, with long curving bends, sections of tight hairpins, and views down into green gorges. The road to Cerkno and the one toward Žiri are both rewarding, with good tarmac, moderate traffic and a steady stream of corners that suit a bike well. Weekends bring cyclists and other riders, so stay on your side of the line, and be careful with gravel on shaded bends after rain. Spring and early autumn are best, when the beech woods are bright and the light is clear.
Idrija is large enough for fuel, groceries and cafés, and there are plenty of places to sit down by the river. A day here works well when you walk the old town on foot, so park near the centre and leave the helmet behind for a couple of hours.