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.
Ah, that explains the extensive use of wood and plastic. That environment would be a nightmare for anything made of steel.