Poland’s underground salt city hides 245km tunnels and carved cathedral

A 245km network of tunnels distributed over nine levels hides one of Poland's most astonishing works of architecture and life. While visuals might deceive you into believing it's some grand mall, what truly lies in front of the eyes is an underground city made up of salt, which is one of the best-kept secrets about the country.Located near Krakow, the Wieliczka Salt Mine reaches approximately 327 metres in depth. Exploited for centuries, the extraction from the mine ceased in 1996 and today, it functions as a tourist attraction and UNESCO World Heritage Site.A natural wonderThe formation of the reserve began about 13.5 million years ago, when a sea that occupied part of Europe receded due to the movement of tectonic plates. The process left open large salt deposits called halite under the region near the Carpathian Mountains.