Gradina is on the hill right above the harbour. It was most probably built in turbulent periods of late Antique, when a great Byzanthine emperor Justinian
whiped away East Gots from Illyrcum and raised many fortreses along the coast in order to provide safe navigation. The staircase and the path leading to this most significant cultural monument, and an excelent lookout as well, was built in 1936.
Thus, on the slopes of hill Gradina that dominates with the harbour examples of hand-made prehistoric pottery were found, that along with remains of walls, show that a prehistoric settlement was there.
If the word Trpanj comes from a verb "trpjeti", meaning to endure, to suffer, to bear, then the name represents the sufferings that first inhabitants had to endure since the nature did not give them furtile land and wide fields to cultivate successfully.