Pećinska church
The Church of Holy Apostles Peter and Paul, known as the Cave Church (Pećinska crkva), is a Serbian Orthodox cave-church located on eastern slope of Mount Kopaonik near Lukovo, southern Serbia. it was built by the Serbian King Milutin (1282 - 1321) in the 14th century and is dedicated to Saints Peter and Paul. It is part of the Monastery of St. Archangel Gabriel (manastir Sv. Arhangela Gavrila).
Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).