Signatures have been present in the Passage of Old Signatures inside Postojna Cave since the 13th century, with the oldest signature dating back to 1213. The Republic of Slovenia marked the 800th anniversary of the start of Postojna Cave tours by issuing a commemorative coin, which features a stylised spiral illustrating the cave's size and age.
The card also features a ten-stotin (i.e. ten-cent) coin with an image of Proteus anguinus (i.e. an olm). The coins were in circulation in Slovenia between 24.4.19