A fascinating mix of underground passages, galleries and halls, an amazing diversity of karst phenomena as well as an easy access are the reasons why Postojna cave is visited and admired by so many tourists. In the last 200 hundred years the cave has been visited by 34 million people. It is certainly the best-known cave in the world and the greatest tourist attraction in Slovenia as well as one of the greatest karst monuments in the world. A lot of books and articles have been written about Postojna cave and at least 100 guide books have been published in 200 years.