Picture taken from > PizzaTravel (more pics there)
Salina Turda (Wikipedia page)
Salina Turda is a salt mine in the Durgău-Valea Sărată area of Turda, the second largest city in Cluj County, northwest Transylvania. Opened for tourists in 1992, the Salina Turda mine was visited by about 618,000 Romanian and foreign tourists in 2017.
There’s an awesome 3 level trampoline park in an old slate mine in Wales. I think its called Bounce Below. They use an old miners train to transport you in and out of the slate mine. Been there once with a school trip!
I went 10 years or so ago. It was awesome.
There’s also a massive zip line over the quarry, which we also did.