On the hill above the port of Trpanj there is an archeological site with the remains of the Gradina fortress. The fort was built in the late antique period. It was most likely built by the Byzantine emperor Justinian, who expelled the Eastern Goths from Illyricum and had a series of fortifications built on the Adriatic coast, to ensure unhindered navigation. Remains of two towers, walls and a cistern can be discerned. Remains of prehistoric pottery and traces of dry stone walls have also been found here, suggesting that there was a prehistoric settlement.
From Gradina there is a beautiful view of the port of Trpanj, the island of Hvar and the entire Neretva channel. The site can be easily reached by stairs from the port.