During 1970–2 three sites on the western defences of the lower Roman and medieval town were examined. The earliest defences, which consisted of a rampart fronted by a stone wall 5 feet (1·5 m.) wide, and a ditch-system, were built in the late second or early third century. At some later date, interval-towers were added to the back of the wall: that at The Park was replaced by a new gateway which was rebuilt in the later fourth century. There was slight evidence that the other gate presumed to lie on the west side of the lower town at West Parade was rebuilt at the same time. North of this, on Mother by Hill, the third-century interval-tower was partially demolished in the fourth century and replaced by an internal platform. There was contemporary thickening or rebuilding of the wall at various other points, including either side of the gate at The Park. At some time in the late Roman period a new wider ditch was dug.
The Roman defences continued substantially in use throughout the medieval period, although the gateway at The Park was no longer functioning. In the thirteenth century the line of the western defences was extended southwards to the Brayford Pool, terminating in the circular Lucy Tower. North of the tower, the new defences comprised a stone wall 7 feet (2·1 m.) wide and a ditch whose size could not be determined.
The excavations also revealed interesting but fragmentary information about occupation within the defences. There were Roman buildings as far south as The Park from the Flavian period.