I visited this WHS in June 2016. The Big Mine has been closed for the last couple of months because of a general strike. Luckily an agreement has been reached and access to the pit should be back to normal soon. However, if you happen to visit on a sunny day I'd suggest you visit the Blaenavon Iron Ore Mountains in the Brecon Beacons National Park from where the iron ore was sourced. The surrounding natural environment has fully recovered and there are several sheep, lambs, badgers, ponds, etc. for an enjoyable hike. Just be careful while driving as you're likely to find sheep crossing the road or just lazing about. A visit to the Blaenavon Ironworks is a must. Not only because of the official UNESCO plaque (and a beautiful manhole commemorating Blaenavon's inscription in English and Welsh), but also because of the interesting 'vintage-looking' information boards, the museum-like cottages from 1790 to the 20th century and the audiovisual presentation (picture). In brief, the workers prepared coke, Blaenavon rocks or iron ore and limestone in the upper yard above the blast furnaces. Then they tipped them from above and used the engines to blow in air through a network of pipes. At more than 1500 degrees Celsius, the iron melted and the molten iron was 'tapped' and guided into channels in the sand to form iron pigs. The workers then drained the waste slag and transported it away in trams. I was lucky to visit on World Heritage Day and not only was the entrance to the ironworks free but there was also a small fair in town where I bought some lamb pastries. Having visited quite a number of mines, I didn't miss not wearing a hard hat for once but if you have the time or you happen to visit on a wet day, go for it.