File:Komárno, an impregnable fortress.jpg

English: Because of the trading and military importance of river crossings, they have played a strategically significant role for thousands of years. Komárno’s earlier settlements controlled the waterways of the Danube, Váh and Nitra rivers. Not only did they control the rivers, but also the roads that went through the Nitra River valley. This placed the occupants of this junction in a key position. Fortress in Komárno at the end of the 17th century

Owning this important international trade intersection (being no other crossing nearby) meant one had power over the region. It is likely, though not proved, that the Romans, who usually secured all the river crossings and confluences, built the first fortress within the Limes Romanus in the location of the present Old Fortress. The area of the present town situated on the right bank of the river Danube belonged to the region of Brigetio (Szőny), which was situated slightly to the east.

After the defeat of the German Quadi people, the Roman Emperor Marcus Aurelius also ordered fortresses built on the left side of the river in 171. One of these fortresses can be found 4 km from Komárno, in the region of Iža (Celemantia – Leányvár). The encampment, which was surrounded by earthen ramparts, was built under the reign of Domitianus. These ramparts were later strengthened with stone walls by the soldiers of the first Roman legion. Some centuries later the stone walls of the encampment were demolished, and a significant part of the material was used for the building of the so called “Old Fortress” in Komárno. It has not been proved yet whether a similar Roman fortress existed in the territory of the present Old Fortress.