I visited Idrija, Slovenia in April 2014. I wasn't expecting much as I'm not so keen on industrial WHS. However, I was pleasantly surprised with Idrija. It is quite remote and you won't visit by chance, that's for sure. It's a nice drive through winding roads and it has much to offer even though it appears to be a ghost town now. The industrial landscape is immediately visible with metallic structures, smelting plants, mines and several shafts. I visited Anthony's shaft in time for the 10am tour in English (the other guaranteed tour is at 3pm). The tour in "the second largest mining site in the world" takes around 2 hours including a 20 minute informative video. You get to wear a protective waterproof miner suit and a hard hat before entering the mercury mine. The guide makes the trip interesting and describes the miners' everyday life as well as the different developments over time. The highlight of my trip was actually seeing naturally occuring mercury droplets in the mine as well as getting to appreciate the different structures (wooden and iron) used to support the shaft. For those who are more adventurous, group tours can be organised to go even deeper inside the shaft with torches instead of electricity lighting and going down ladders apart from the 500 stairs you go down in the traditional tour, eventually getting out in the nearby village. The traditional loop was more than enough for me to grasp the size and importance of this industrial site. I would vividly recommend using the hard hat if you're taller than 6 feet ... you'll definitely won't regret it! Apart from the mine, there's a worthwhile hike through the greenery to see the Kanomilja or Ovcjak Water Barrier, the Vojsko-Idrijca Water Barrier, the Putrih's Water Barrier and the Belca Water Barrier. If you have enough time go for it, otherwise I'd highly recommend visiting the shaft and the old town itself, with its church, municipal museum, castle, old cinema, etc. It might be quite difficult to find an open restaurant in the slow months but do try the local speciality "zlikrofi". All in all, I enjoyed my visit even though it isn't one of the most outstanding WHS in the list.