Blagaj Fortress

Archaeological material scattered across the slopes of the karst hill above the Buna's source points to settlement here in the prehistoric and Roman periods. Each of the hill's three summits carries its own remains: on the north-eastern summit a Roman or late-antique watch-post, known as Mala gradina, on the south-eastern summit the contours of a prehistoric hillfort, and on the south-western summit the fort later known as Stjepan grad, built up in the medieval and Ottoman periods. It is possible the site formed a twin settlement of Old Fort and Mala gradina into at least the mid-tenth century. The earliest indirect written notice of the Zahumlje forts, Blagaj among them, is the Byzantine emperor Constantine Porphyrogenitus's Treatise on Peoples, composed between 948 and 952, which names two strongholds in the district, Bona and Hum.

After the tenth century Blagaj played an important role in the development of Hum. A major route linking the Adriatic to the Bosnian hinterland ran along the Neretva valley nearby. Miroslav, prince of Hum, held court at Blagaj and built a church there dedicated to Saints Cosmas and Damian; a Cyrillic-inscribed plaque recording the church's construction, found in 1912 near the ruins of the manor at Bišće, is now held in the National Museum of Bosnia and Herzegovina. By the time of King Tvrtko, Bosnian rulers were issuing charters from Blagaj.

In May 1404 Blagaj became one of the residences of Duke Sandalj Hranić, and afterwards of herzeg Stjepan Vukčić Kosača, after whom the town named the fort Stjepan grad. The first written reference to the fortress itself is a peace accord Sandalj concluded with Venice on 1 November 1423, issued "in our town of Blagaj"; it was also named in fifteenth-century charters of Alfonso V, king of Aragon and Naples. The Ottomans took Blagaj in 1465, and a kadi of Blagaj is on record by 1473. They repaired the fort twice, restoring the west tower in 1699 and again in 1827, and kept a garrison there until 1835, by which point the fort's earlier strategic role had passed to Mostar.

The largely preserved walls, 12 to 14 metres high, trace an irregular polygon above vertical cliffs to the south, west and north, reached by a 900-metre serpentine bridle path and entered through a gatehouse in the thicker eastern wall. That east wall was badly damaged in the 18th or early 19th century when a large quantity of gunpowder exploded in its middle tower; the repairs that followed were carried out crudely and altered the fort's original appearance. Excavations in 1965, directed for the National Museum of Bosnia and Herzegovina, investigated some 1,000 square metres, over a third of the walled area, recovering medieval pottery, ironwork and roughly 700 kilograms of lead from the ruined palace, alongside a scatter of Illyrian pottery and Roman roof-tile fragments. The fortress remains state property, protected since 6 December 2003 as a National Monument of Bosnia and Herzegovina.