Somewhere beneath the ordinary streetscape of Naas, a medieval walled circuit is almost entirely absent from view. No section of wall stands to any appreciable height, no gate survives, and the course of the defences can only be traced in fragments, through trenches opened for pipes and foundations, and through the occasional ditch encountered during development works. What makes the situation quietly remarkable is not the absence itself, but the long paper trail of urgency that preceded it, and the degree to which the physical reality still eludes us.

The documentary record begins in 1415, when the Crown granted the provosts and burgesses of Naas the customs of the town for twenty years specifically to fund its fortification. Murage grants, which were permissions to collect tolls in order to finance the building or repair of town walls, continued to be made by parliament between 1451 and 1468; the 1468 grant carried an unusually frank justification, describing the town as 'like to be destroyed or burned, unless it is walled'. Further charters in 1568 and 1609 again assigned tolls to the Corporation for walling purposes, and Charles I made a grant in 1629 towards repairing 'their buildings and walls'. At least six named gatehouses are known from historical sources: the North Gate, Iago's Gate, and the Watergate Castle on the north and east; Corban's Gate near the junction of Corban's Lane and Church Lane; the Green Gate at the south end of the town boundary; and the West Gate near New Row. A feature known in old leases as 'The Barrier' or 'North Barrier' adds a further puzzle, with scholars divided over whether it marked an inner defensive line, the original northern boundary of the town, or something else entirely.

What archaeology has recovered is fragmentary but suggestive. A possible defensive ditch was identified near Corban's Lane in 1996, and a substantial linear ditch on Friary Road in 1998 was considered consistent in position and orientation with the defensive circuit. In 2002, work at Poplar Square and Friary Road uncovered a large ditch, between four and five metres wide and up to 1.4 metres deep, running roughly northwest to southeast near the site of Eustace Castle. The most tantalising find came in 1999 on the Dublin Road, where a wall fragment emerged: only 1.5 metres long as exposed, but at least 1.1 metres wide, preserved beneath the foundations of a later cottage. Two rough courses of stone survived to a maximum height of 43 centimetres. It was left in place beneath the site. Whether it belonged to the town wall or to the nearby North Gate remains an open question.