1911 Encyclopædia Britannica/Adelsberg
ADELSBERG (Slovene Postojina), a market-town in Carniola, Austria, 30 m. S.S.W. of Laibach by rail, Pop. (1900) 3636, mostly Slovene. About a mile from the town is the entrance to the famous stalactite cavern of Adelsberg, the largest and most magnificent in Europe. The cavern is divided into four grottoes, with two lateral ramifications which reach to the distance of about a mile and a half from the entrance. The river Poik enters the cavern 60 ft. below its mouth, and is heard murmuring in its recesses. In the Kaiser-Ferdinand grotto, the third of the chain, a great ball is annually held on Whit-Monday, when the chamber is brilliantly illuminated. The Franz-Joseph-Elisabeth grotto, the largest of the four, and the farthest from the entrance, is 665 ft. in length, 640 ft. in breadth and more than 100 ft. high. Besides the imposing proportions of its chambers, the cavern is remarkable for the variegated beauty of its stalactite formations, some resembling transparent drapery, others waterfalls, trees, animals or human beings, the more grotesque being called by various fanciful appellations. These subterranean wonders were known as far back as 1213, but the cavern remained undiscovered in modern times until 1816, and it is only in still more recent times that its vast extent has been fully ascertained and explored. The total length of the passages is now estimated at over 5 ½ m. The connexion with the Ottokar grotto was established in 1890. The Magdalene grotto, about an hour's walk to the north, is celebrated for the extraordinary subterranean amphibian, the proteus anguinus, first discovered there. It is about a foot in length, lives on snails and worms and is provided with both lungs and gills.