Today Salina Turda has become an unlikely tourist attraction, with thousands of visitors descending its vertical shafts each year to play mini-golf, go bowling and row around its underground lake. This submerged wonderland even has a healing center for people with lung conditions.

British photographer Richard John Seymour recently traveled to Salina Turda in his quest to document human-altered landscapes. "Photographing this space was a challenge due to its sheer scale. Humans are put into perspective and the difference between nature and man-made features is blurred."

Salina Turda filled the coffers of Hungarian kings and Habsburg emperors -- especially during the 13th century, when salt was more valuable than gold -- and sustained the local community for centuries.

Since mining activity ceased in 1932, it has had many lives. It was used as a shelter in World War II and has even served time as a cheese storage center. Salina Turda reopened as a visitor attraction in 1992, bolstered by €6 million investment 16 years later, which cemented its adaptive reuse as a museum and theme park.

(CNN)