Postojna Cave

Postojna Cave (Postojnska jama, German: Adelsberger Grotte, Italian: Grotte di Postumia) is a 24.34 km (15.12 mi) long karst cave system near Postojna, southwestern Slovenia. It is the second-longest cave system in the country (following the Migovec System) as well as one of its top tourism sites. The caves were created by the Pivka River.