The Civil Town had a town wall from at least the first half of the 2nd century.
A double moat surrounded the 160 cm-thick walls on the outside and behind the walls ran an earth embankment for patrolling guards. The walls, reinforced with ditches, and in the west also with towers, had gates on all four sides. The wall’s path was often modified during the four centuries of Roman rule. A part of the town wall and moat, as well as a section of the aqueduct crossing the wall, can be viewed by the northern gate.
In the late Middle Ages, a gunpowder mill was constructed on the strong foundations of the gate towers. It was in this mill that an exhibition of Aquincum finds was opened in 1888. The remains of the gate towers cannot be viewed.