About 100 kilometres from Bucharest and 44 kilometres from Ploiesti, the Slanic salt mine is a recognised destination for balneal and touristic activities since 1853, when it was declared a tourist destination of national interest in Romania.
Among the superlatives of the salt mine (especially the Union Mine), the most important tourist and health objective in the resort, there is a huge volume of excavated salt, about 2.9 million cubic metres, which led to the creation of cavities with gigantic volumes, respectively 14 trapezoidal rooms totaling about 80,000 square metres.
The 14 underground rooms have an opening of 10 metres to the ceiling, 32 metres wide at the bottom, and the height is 54 metres. The depth of the salt mine is 208 metres. The impressive dimensions granted it the title of the largest salt mine in Europe.