For decades, the line of the old town defences was legible in the alignment of property fences and garden walls along the north side of the settlement, a quiet fossilisation of the medieval layout that persisted largely intact until the mid-1990s. Housing development from that point onwards has obscured much of it, but the line has not been entirely erased; it simply requires knowing where, and how, to look.

The medieval town was roughly rectangular, covering somewhere between twelve and nineteen hectares, laid out on an east-west axis with burgage plots, the long narrow land parcels characteristic of medieval planned towns, running north and south from the main street to the defences. The southern boundary was a stone wall, shown on a 1710/11 map by White running north-west to south-east from Gowran Castle to the town's edge. The northern boundary was a different matter: not a wall but an earthen rampart and ditch, described on the same map as 'The Rampart or Trench'. The document evidence for the walling effort comes from a single murage grant, a royal licence allowing a town to levy tolls specifically to fund the construction of defensive walls. In 1415, the Patent Rolls record that the town, then called Balygaveran, had recently been burned by Irish enemies, was remote from English military assistance, and was given a forty-year grant of tolls to fund walling its streets and carrying out other necessary works, with accounts to be rendered before the Earl of Ormond. By around 1550, a rental account in the Calendar of Ormond Deeds lists seven town gates, including 'Maugdelin barre' at the east, 'West barre', 'Castell barr', and 'Tibirdowanis barr', the last of these possibly a corruption of Tobar an Domhnaigh, meaning Sunday's Well. An internal gate also appears in the historical record, and its presence has prompted debate: it may indicate that the town contracted at some point, requiring the outer gate to be moved inward, or alternatively that the town later expanded westward to absorb what had been an external fair green.

A series of archaeological excavations carried out ahead of housing developments from the 1990s onwards has produced a detailed, if piecemeal, picture of the northern defences. The ditch uncovered across multiple sites was not uniform; it was deeper and wider towards the east, where the ground is higher, narrowing and shallowing as it followed the slope westward, reaching around six metres wide and one and a half metres deep at the east and reducing to roughly four metres wide and one metre deep further west. Traces of an internal earthen bank, probably thrown up from the ditch spoil, were identified in several places. Foundations of a mortar-bonded wall roughly 0.7 metres thick, possibly the town wall, were also found to the south of the town during a separate investigation. Taken together, the excavations confirm that Gowran's medieval defences were a real and substantial system, not merely a paper ambition, even if almost nothing of them survives above ground today.