Postojna cave Slovenia

Postojna Cave (Slovene: Postojnska jama; German: Adelsberger Grotte; Italian: Grotte di Postumia) is a 24,120 m long karst cave system near Postojna, southwestern Slovenia. It is one of its top tourism sites.Postojna Cave was carved by the Pivka River over millions of years.nThere are stalagmites, stalactites, and formations called curtains or draperies that look like folded curtains.
The cave system is 24.12 kilometers long and is made up of four caves interconnected through the same underground river. The caves are also home to the endemic olm, the largest troglodytic amphibian in the world. The tour through the caves includes an aquarium with some olms in it.
History
The cave was first described in the 17th century by the pioneer of study of karst phenomena, Johann Weikhard von Valvasor, although graffiti inside dated to 1213 indicates a much longer history of use. In 1818, when the cave was being prepared for a visit by Francis I, the first Emperor of the Austria-Hungary, a new area of the cave was discovered accidentally by Luka Čeč, a local man in charge of lighting lamps in the cave.
In 1819, Archduke Ferdinand visited the caves, this is when the caves became officially known as a tourist destination. Čeč became the first official tourist guide for the caves when the caves were opened to the public. Electric lighting was added in 1884, preceding even Ljubljana, the capital of Carniola, of which the cave was part at the time, and further enhancing the cave system's popularity.
In 1872, cave rails were laid along with first cave train for tourists. At first, these were pushed along by the guides themselves, later at the beginning of the 20th century a gas locomotive was introduced.
During World War I, Russian prisoners of war were forced to construct a bridge across a large chasm inside the cave.
During World War II, German occupying forces used the cave to store nearly 1,000 barrels of aircraft fuel, which were destroyed in April 1944 by Slovene Partisans. The fire burned for seven days, destroying a large section of the cave and blackening the entrance.
After 1945, the gas locomotive was replaced by an electric one. About 5.3 kilometres of the cave system are open to the public.
At the end of the 1990s it was one of world's most visited show caves, with nearly 1 million tourists per year.

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