Thanks to Mateja for sending this lovely stamp on cover. Another great addition from my want list. I am looking for Austrian side issue. If any of you ready to trade Please contact me through snail mail.
Postojna Cave is located in Western Slovenia and it is a network of 20 Kilometers of Passages, Galleries, Chambers and of course, a Post office. It is the largest cave in the "Classic Karst". Karst means landscape formed by the dissolution of a layers of soluble bedrock, such as limestone or dolomite. This cave was first discovered in the 17th century and opened to the public in 1819.
The cave management asked Austria to open a post office inside the cave. In 1899 August 15th, Austria finally opened the first underground cave post office in the world, near Kongresna Dvorana 500m inside the cave from the entrance. Until 1911 the post office was operated only on special occasions. Even during WWI the underground post office stayed open and continued to operated till 1927.
After the Annexation of this cave to Italy, in May 1927 Italy replaced this stone post office with a new building 1.4 Km away from the entrance.
In the last 196 years more than 3.5 crore people visited the cave and the Cave Post Office. It is the most visited cave in Europe.
At first the mails carried the special cancellation "Adelsberger Grotte - Postojnska Jama" and after it came under the Italian authorities it carried "Postumia (Grotte)" special cancellation.
Even though the cave is in Slovenia, Austria Post opened the First under ground cave post office. So no wonder that Slovenia and Austria joint hands to issue the Joint MS on this historical Postojna Cave ion 6th April, 2013.
In 1872, railway lines were laid in the cave and railway cars were pushed by the cave guides. Then they used gas locomotive to carry the tourists. In 1884, electricity connections arrived. Today, tourists take the electric train.
The cave was used for many purposes. It was used as storage room, a hideout, a bunker and of course a concert Hall. During World War II Germans used this cave as an fuel depot. Since the Italians took all the maps of the cave, the Germans with limited knowledge about the cave were not aware of the back side entrance and they didn't guard it. The partisans took this opportunity to enter the cave through Crna Jama and used the artificial tunnel dug by the Italians to enter the cave from behind and set the fuel alight. The fire took seven days to die-out and it destroyed a huge part of the cave.