While this may look like an alien-base from an upcoming science fiction thriller, it's actually located right beneath our feet, the old Salina Turda Salt mines in Transylvania, Romania to be exact. It's the world's largest salt mine museum and was originally established in the 17th century. They were formed completely by hand and machine rather than by using explosives. Continue reading for a video, pictures, and more information.
My Modern Met reports that "throughout the cool interior, which averages about 50-55°F with 80% humidity, there are a variety of mines, rooms, and spaces to be explored. At almost 140 feet down, Rudolph Mine offers a 180-seat amphitheater, a carousel, ping-pong tables, basketball hoops, mini-golf, and bowling. Old machinery still stands within the underground expanse and some of it is used to lead people on tours."