Trimammium is located on the Danube riverbank, in the Stalpishte locality, which stands around 3 km to the northwest from the village of Mechka, Rousse region, and 22 km to the southwest from Rousse. The local population calls it “Kaleto”. Its area is around 24 decares. The fort is localized on the base of the field observation work by Karel Skorpil and Mihail Vankov in 1905. They also described the belonging unfortified settlement and necropolis. The evidences for a rock relief of the Thracian horseman and a rock-hewn church at the dry-land of the Oreshe river are particularly interesting. A very small section of the fortification wall of Trimammium is studied, and for this reason its chronology is not entirely cleared. The last remains are from the period of the Second Bulgarian Kingdom – as structures, these are a dwelling and a small single-nave church. 11 imitation scyphates refer to this period. Probably the end of the settlement was put during some of the 13th-century Tatar invasions.