Some 203m high in the old town, a hill contains the sparse ruins of Eumolpias, a Thracian settlement in 5000 BC. The fortress and surrounding town enjoyed a strategic position, later bolstered by Macedonians, Romans, Byzantines, Bulgarians and Turks, who named it Nebet Tepe (Prayer Hill).
While the remaining rubble is rather formless, the site does offer great views. Get there from ul Dr Chomakov (the continuation of ul Sâborna). Partially restored remains of a 13th-century reservoir are also here.