|Citadel is a convention for relatively small tract in the ancient city, which is limited with walls (curtain walls 18–21) on the four sides. The citadel occupies a low section of the Karantinnaya Bay coast, which makes bed and east side of nameless ravine flowing into the Karantinnaya Bay.
Excavations of this area started in 1897 by K.K. Kostsyushko-Valyuzhinich. The investigations were conducted by K.E. Grinevich in 1920s, by V.V. Borisova in 1960s, by I.A. Antonova, S.B. Sorochan and others later on.
During this period, the excavations in the Citadel uncovered public baths from the Roman Period, large administrative buildings from the Roman and Byzantine Periods, complicated system of drains, and other constructions.