Idrija

For almost five hundred years the second-largest mercury mine in the world ran beneath this small town, wedged into a forested valley west of Ljubljana. The mine opened in 1490 and closed in 1995. In between it produced something like 13 percent of all the mercury ever mined on Earth and made Idrija the second town in the Habsburg lands to get electric street lighting. It also fed a parallel craft tradition that has long outlasted it: Idrija lace, taught in the world's oldest continuously running lacemaking school, founded in 1876.

Mine and lace together were inscribed on the UNESCO World Heritage list in 2012, as part of a transboundary site shared with Almaden in Spain. Walk the town and the inheritance is everywhere: miners' houses on the slopes, the Gewerkenegg castle from which the Habsburg authorities administered the mine, the surviving water-driven Kamšt pump that lifted mine water until the 1940s. The old kilns that roasted mercury ore still stand in Hg Smelter Park.

None of this has turned the town into a museum. The lace school is full of teenagers. The Kendov Dvorec hotel is an actual hotel, not a stage. And the local žlikrofi, small pinched-pasta dumplings filled with potato, onion and bacon that carry EU traditional-speciality (TSG) status, turn up on every restaurant menu without ceremony.

Come in May, June, September or early October, for long days and walkable trails into the surrounding Idrija Geopark; the cultural calendar is at its fullest then too. The Idrija Lace Festival in late June is the year's anchor event, when the lacemaking school hosts open classes and a competition draws makers from across the region. July and August stay warm but never crowded, and the mine holds a constant 12°C, a welcome retreat from the heat. Winter changes the character of the Geopark trails entirely, but the smaller restaurants and several guesthouses close from December to mid-March. The Christmas markets are modest; visit them if you are in the region anyway.

From Ljubljana the route is straightforward by bus: Arriva-Alpetour runs a regular service from Ljubljana to Idrija (around one hour and fifteen minutes), several times a day on weekdays. The nearest railway station is Logatec, on the Ljubljana–Postojna line, with a connecting bus to Idrija (about thirty minutes). From the coast or Italy, the most efficient route is via Postojna with a change. No direct train serves Idrija; the post-industrial irony is that the mine's own narrow-gauge railway closed long before passenger service ever reached the town. A car is not required. The town centre is small enough to cover on foot, and the Geopark trails start from the edge of town.

Kendov Dvorec, in the hamlet of Spodnja Idrija five minutes down the valley, occupies a fourteenth-century manor with rooms furnished in regional antiques; it is the area's standout if the rates suit (check rates and operation directly). In Idrija itself, the Hotel Jozef is a compact business-style hotel by the bus station with reliable rooms and good local food in the restaurant. Pension Barbara, named after the patron saint of miners, is a family-run guesthouse with around a dozen rooms. The tourism office on Mestni Trg keeps a current list of farm-stays in the surrounding villages, the sensible choice for a longer visit or for walking the Geopark trails systematically. Skip the roadside motels on the Tolmin–Ljubljana road. The centre of Idrija is more interesting.

The dish to order is idrijski žlikrofi: small dumplings folded in a distinctive hat shape, filled with potato, onion and bacon, traditionally served either in broth or with bakalca, a slow-cooked lamb-and-vegetable ragout. They have held EU TSG status since 2010. Gostilna Pri Skafarju, in the town centre, makes them the way the lace teachers' mothers did. Kendov Dvorec serves a more refined version on its tasting menu. Beyond the žlikrofi, the kitchen takes whatever the Idrija forests provide: porcini in autumn, venison in winter, freshwater trout from the Idrijca year-round. Drink the local beer (Pivovarna Human in Spodnja Idrija) or the wines of Vipava just to the south-west. Sunday lunch at Gostilna Mlakar is the institution to know about.

Take the Anthony Main Road mine tour, Antonijev rov, through the oldest preserved section of the mine: about ninety minutes descending through five centuries of mining technology, at a steady twelve degrees whatever the weather is doing above. Walk up to Gewerkenegg Castle for the municipal museum, where the mercury rooms are the heart of it and the lace rooms the essential counterpoint, and visit the Idrija Lace School during term to see classes in progress. Then follow the water. The Rake, a channel cut in 1604 to bring the Idrijca to the mine's machinery, still runs, and the level path beside it is the town's best short walk, passing the memorial botanical garden named for Giovanni Antonio Scopoli, the naturalist who served as Idrija's first mine doctor, and one of the largest ash trees in Slovenia.

Beyond that lie the Kamšt pump and the Hg Smelter Park, where the old roasting kilns still stand. The Idrija Geopark is wider than the town and has a network of marked trails through the karst landscape; the best of them climbs to the Wild Lake, Divje jezero, at once a spring, a lake and a cave, and Slovenia's first natural monument. The Klavže, the sixteenth-century water barriers built to float mine timber down the gorges, make a half-day walk you will probably have to yourself. A longer route through the Upper Idrijca Landscape Park, around 27.5 kilometres and easier on a bike, strings together the Strug tectonic window, the river potholes known as bučke and the bathing pools at Lajšt. The Feldban, a First World War military narrow-gauge line from Godovič, can be walked alone or with a guide.

The calendar is worth planning around. The Idrija Lace Festival in late June is the year's anchor, when the school opens its classes and a competition draws makers from across the region; the žlikrofi festival at Park Mejca celebrates the pinched potato dumplings that were the first Slovenian product to win EU Traditional Speciality Guaranteed status, though dates shift, so check. Runners have the Hg Trail across the Geopark, with fourteen, twenty-seven and fifty-kilometre options. Further out, at Dolenji Novaki near Cerkno, the Franja Partisan Hospital — a secret wartime hospital built into a ravine, run by the Idrija municipal museum and carrying the European Heritage Label — makes an unforgettable half-day, but it has been closed at times after flood and storm damage, so check before travelling.

• Language: Slovenian; English in tourism contexts; Italian and German common with older residents
• Currency: euro
• Plug: European type F/C
• Money: ATMs in the town centre; cards accepted in restaurants and hotels, cash useful at smaller bars and the lace shops
• Seasons & hours: The mine tour requires a guide and is booked at the Anthony Main Road ticket office or in advance online
• Mobile: Mobile coverage is solid in town and patchy on the Geopark trails
• Nearest hospital: Idrija (small) and Ljubljana (full)