The remains are not visible to anyone walking past today, but their discovery during construction work in 1996 quietly complicated what had seemed a well-understood part of the city's post-medieval landscape. What was found was not a river or a natural stream, but a deliberately cut channel, and then another, and then evidence of both being rebuilt in stone around 1600, and then reused again as a drain in the Georgian period, each layer of pragmatic reuse sitting atop the last.

The excavation, carried out in July and August of 1996 by archaeologist Linzi Simpson on behalf of Margaret Gowen and Co. Ltd., was prompted by documentary references to a medieval watercourse known as the Glib water, which was believed to run through the NCAD site. The college grounds occupy a steep north-facing slope that drops sharply towards the Liffey, and it was into the natural boulder clay of this slope that the original U-shaped channel had been cut. At its southern end it measured 3 metres wide at the upper level, narrowing to 0.8 metres at the base, and its silted fill contained a significant quantity of Anglo-Norman medieval pottery. A second, badly damaged watercourse was found running along the eastern boundary of the site, feeding into the first. Both are thought to have served three water-mills owned by the nearby hospital of St John the Baptist, a religious foundation established outside the walled town of Dublin in the late twelfth century. By the time of the Dissolution in the sixteenth century, the hospital held three mills in the immediate area, and John Speed's map of Dublin, dated 1610, marks them plainly as 'The mills', standing opposite what the map labels 'John's House', outside the city walls to the south-west of Ormond's Gate. Around 1600, the earlier earthen channel was replaced by a well-faced limestone-lined channel measuring 0.9 metres wide by 0.7 metres deep, with a flagged base that was later pressed into service as a Georgian drain.

There is nothing to see at the site directly; the watercourse lies beneath a working college campus, and the archaeological deposits were significantly disturbed by deep Georgian cellars and later concrete piles before the 1996 excavation could record them. The value is cartographic and documentary as much as physical. Speed's 1610 map, which can be examined in reproduction in many Dublin libraries and online, traces what appears to be the same watercourse running east to west along St Thomas Street, passing the northern side of St Catherine's Parish Church before turning south towards Thomas Court. Following that route on foot today, along Thomas Street and down towards Usher's Quay, gives a reasonable sense of the course the Glib water once took on its way to the Liffey.