Survey work being carried out on the one and a half miles of mainly 12th to 14th-century medieval defences have revealed nine small stretches where the original third-century AD Roman wall still survives. Detailed examination of the ramparts has shown that thousands of blocks of Roman basalt building material still makes up parts of the facework of the defences.
In one 18yd (16.5m) stretch of wall the Roman facework masonry has been found to survive to a height of 12ft (3.6m).
Excavations have also revealed the remains of a timber city gate 30ft (9m) wide, built between AD160 and 180.
Exeter's defences were begun AD55 when the site was a 40- acre Roman fortress. A town, known as Isca Dumnoniorum, home to the Dumnoni tribe, developed within the earth and wood fort walls after about AD75 and expanded its defences to enclose 93 acres in the late second century. Then in the early third century the city fathers had a stone wall built.
Some 75 per cent of this defence system, largely refaced in medieval times, still survives today, and Exeter's archaeologists have found that the original Roman basalt facing is still in place along some stretches.
The wall, which is being renovated by Exeter City Council, has a colourful history. It endured, albeit never successfully, seven sieges; in 893 and 1003 at the hands of the Danes; in 1067 for 18 days by William the Conqueror; in 1497 for just two days by the pretender to the throne Perkin Warbeck; in 1549 for five weeks by Cornish Catholic rebels; in 1643, for three months by the Royalists; and in 1645/46 for seven months by the Roundheads.
In its time, the wall has seen both comedy and cruelty. In 1967 one of its Anglo-Saxon defenders sought in vain to help drive William the Conqueror away by standing on top of the city wall and breaking wind in the Norman leader's direction.
The wind of a different variety, however, was used by Exeter's textile manufacturers to dry their cloth, which they had the habit of hanging from the ramparts - that is until 1641, when the city fathers banned the 'very prejudicial' practice in case the weight brought the decrepit masonry tumbling down.
But Richard III developed a more unfortunate use for the ramparts by displaying along it the heads of rebels 'placed in basins'.
Exeter City Council is planning a archaeological survey of the wall next year.
It is currently engaged in a programme of renovation and conservation, which is opening up previously inaccessible areas to the public.