Blagaj is a village-town in the south-eastern region of the Mostar basin, in the Herzegovina-Neretva Canton of Bosnia and Herzegovina. It stands at the edge of Bišće plain and is one of the most valuable mixed urban and rural structures in Bosnia and Herzegovina, distinguished from other similar structures in its urban layout. Blagaj was most likely named for its mild weather patterns since "blaga" in Serbo-Croatian means "mild". Blagaj is situated at the spring of the Buna river and a historical tekke (tekija or Dervish monastery). The Blagaj Tekija was built around 1520, with elements of Ottoman architecture and Mediterranean style and is considered a national monument. Blagaj Tekke is a monastery built for the Dervish cults.
Vrelo Bune is the source of the Buna river is a strong karstic spring. The river flows west for approximately 9 kilometres (6 mi) and joins the Neretva near the village Buna. The historic site of the Old Blagaj Fort (Stjepan grad), on the hill above Blagaj, was the seat of Herzegovinian nobleman, Stjepan Vukčić, and the birthplace of Bosnian queen Katarina Kosača-Kotromanić.
During the classical antiquity there existed an Illyrian fortress and a Roman castrum. During the reign of Byzantine Emperor Justinian, several fortified towns were built in the area. Blagaj was mentioned in Constantine Porphyrogenitus’ work De Administrando Imperio as Bona, then part of Zahumlje (Hum).