A murage grant, essentially a royal licence allowing a town to levy tolls on goods in order to fund the construction of stone defences, was recorded in the Chancery Rolls in 1356 to 1357. The Patent Roll of Edward III describes an exemption on certain customs "to the town of Thurlys in aid of the paving of that town and its enclosure with a stone wall." The money was authorised, the intention was documented, and yet no physical trace of a town wall has ever been identified on the ground. Neither the Down Survey map of 1655 to 1659 nor Rocque's map of 1755 shows any such structure. What survives instead is a scattering of clues, some architectural, some linguistic, that suggest a defended circuit of some kind did exist, even if its precise nature remains unresolved.

The town itself was founded in the late twelfth century by Theobald Walter, the Anglo-Norman lord who also constructed an earth and timber motte-castle close to what is now Liberty Square. A motte-and-bailey was a common early Norman fortification type, consisting of a raised earthen mound topped with a wooden tower, and this one, known locally as the Moat, sat in the north-western quadrant of the medieval settlement. The town's vulnerability was demonstrated almost immediately: Donal More O'Brien won a military victory here in 1192, presumably targeting the newly planted settlement. Despite that early instability, Thurles developed into a functioning borough, with documentary evidence of burgage tenure recorded by 1336 and civic administration noted by 1432. A proposed wall circuit, covering roughly 7.5 hectares, would have followed the western bank of the River Suir for approximately 250 metres, then turned towards Black Castle and the motte, leaving the eastern side of town, beyond the river, undefended. Whether Westgate Street takes its name from a gate in that wall, or simply from the gateway of the bawn wall belonging to Black Castle, a bawn being the enclosed courtyard of a tower house or castle, is itself uncertain.

The most tangible physical remnant of any gate structure is the springing arch of the eastern gate, which still protrudes from the masonry of Barry's Castle near the river crossing. The western gate, described in the Ordnance Survey Letters of 1840 as geata na gcoileach, had already been destroyed by that date, surviving only in name. Those same letters also mention a round structure called Crow's Tower, standing to the right of the road towards Cashel, which may have been a mural tower, the kind of projecting turret built into a town wall at intervals to allow defensive fire along the wall face. That tower, too, is gone, leaving Thurles as a town whose defences exist most fully in documents, placenames, and ambiguity.