The River Suir, running along the southern edge of the town, apparently rendered an external defensive ditch unnecessary on that side; elsewhere, excavations along Dowd's Lane revealed both the wall and a fosse, a dry or water-filled ditch, running parallel to it. In all, the wall once enclosed a roughly rectangular area of fourteen hectares, with a northward bulge to accommodate St. Mary's medieval church and graveyard.

The story of how that circuit came to exist, and how long it was kept in repair, is itself worth attention. The earliest recorded murage grant, a royal licence allowing a town to collect tolls specifically for wall-building and maintenance, was issued by Edward I in 1298 for a ten-year period. Further grants followed in 1316, 1319, 1356, and 1364, and in 1409 Henry IV authorised a thirty-year grant. By 1463 the townspeople were being levied directly for upkeep of the South Gate and general wall repairs. When William Camden passed through in 1587 and wrote up the town in his travelogue 'Britannia', he noted that Clonmel was 'well fortified', and the inauguration of the town's Corporation by James I in 1608 recorded that 'great and frequent costs are expended' on the walls. The Civil Survey of the 1650s still described the town as 'walled about with a stone wall of lyme and stone, with severall Turretts'. It was Cromwell's siege of 1650 that began the real deterioration, a large breach opened during the bombardment, and though Williamite forces later reinforced the defences with artillery bastions recorded on J. Goubet's map of 1690 to 1691, the wall's days as a functioning military structure were effectively over.

What survives above ground is fragmentary but genuine. One mural tower on the western stretch was converted into a garden gazebo in the nineteenth century, complete with a broad external staircase and an altered ground floor, though its vaulted first floor remains. Another three-storey tower to the north retains its pointed vault, a Caernarvon-arched window, ogee light, and cross-loop. The north-east angle tower, circular in plan with walls nearly two metres thick, was partially uncovered in 1991. None of the original six gates survive intact, though the West Gate was rebuilt in the nineteenth century on its medieval footprint, and the ground beneath the surrounding streets continues to yield courses of sandstone wherever development breaks the surface.