The underground post offices of Postojnska jama, Slovenia, 1899 - 1945
Trevor R. Shaw, Alenka Čuk - (32/1,2003)
The only cave post offices to have been situated underground were in Postojnska jama. In 1899 the cave management, responding to the growing use of picture postcards, built a stone post office near Kongresna dvorana 500 m from the entrance. It was open by 15 August 1899, with a special "Adelsberger Grotte / Postojnska jama" cancellation authorised by the postal authorities. This building remained in use until 1927 (with the Italian "Postumia (Grotte)" postmark after 1922), when it was replaced by a new building 1,4 km inside the cave. Its last recorded use was 15 August 1945 when the cave was reopened under Jugoslav management.