Locally called Carevi Kuli (the Tsar's Towers), the fortress sits on a high ridge directly above Strumica, a steep but pleasant 30-minute walk up through pine woods from the town centre. The site has been fortified since antiquity — the Romans called the settlement Astraion — but the substantial walls and towers visible today date mostly from the medieval period, when Strumica was a contested border point between Byzantium and the First Bulgarian Empire.
Excavations are ongoing and parts of the site are still being uncovered. There is no admission charge and the views are the reason to climb: the whole Strumica valley spreads out below, with the Belasica mountains forming the Greek border to the south. The interpretive boards are in Macedonian and English, and a small visitor centre has scale models showing how the citadel would have looked in its prime.