I'm so happy I found a forum like this. It's my first time posting but I have been reading for a long time. I would like to share more about the Asturian Industrial Heritage, as I have only seen a thread that talks about the Asturian mining museum, and others about mines in southern Spain. I think that mine explorers and industrial archaeologists will find this interesting.
Asturias (north-west Spain) is a region that has a major concentration of mining heritage sites. Most of you might know the area because of Picos de Europa (worth visiting and exploring) but during the XX century, Asturian coal mining developed at a mass scale during World War I, when the main European producers where involved in the war.
Arnao, the mine in the video, is the first mine in Asturias excavated under the ocean floor.
https://vimeo.com/340451717 https://patrimoniuindustrial.com/en/ It's in Spanish and English.
If you plan to visit Asturias and want to visit some heritage sites, you will definitely need to rent a car. Most of these sites are only accessible by car (no public transport or bus can get there) and some others on foot!