When the Kingscourt line was excavated through a natural spur of land, it sliced the medieval settlement away from the present village, leaving the old church on one side and the living town on the other. The spur itself is a modest geographical feature, a slight ridge dropping away to either side, with a diverted channel of the River Dee running along its eastern edge, a course already fixed by 1698 and recorded on a Gormanston estate map held in the National Library. That combination of a railway trench and a re-routed river gives Nobber an oddly fractured relationship with its own past.

The town's origins lie with the Anglo-Norman plantation of Meath. A borough was probably founded by Gilbert d'Angulo, who also raised the motte that still sits north of the church on its own hill. A motte is the steep earthen mound characteristic of early Norman fortification, usually topped with a timber tower, and Nobber's example survives as a visible presence in the landscape. The d'Angulo family lost favour with Prince John after he was restored as Lord of Ireland in 1196, and the manor passed to the younger Hugh de Lacy around 1200. By 1227 the borough was established enough for its burgesses to be granted four carucates of land and a fourteen-day November fair; mills appear in records from 1211 to 1212, and by 1290 there were formal burgage plots and a charter. The town had a Provost, its own court, and stocks. On de Lacy's death in 1243 the manor passed by marriage to the Fitzgeralds, then through the le Botiller and de Londres families, arriving in 1386 with Christopher Preston, the second Lord Gormanston, whose family held it into the nineteenth century. Nobber sat at the edge of the Pale, and the pressures of that position were real: vacant plots are noted in 1400, the town was burned by Irish raiders in 1425 and again in 1434, with eighty hostages taken in the second attack. Christopher Preston received permission to fortify with ditches in 1436, and a second grant followed in the sixteenth century, though neither appears to have been carried out. By the time of the Civil Survey in 1654 the town still had a Mansion House, two bridges, a mill, and three eel-wears on the Dee.

The wide Main Street, running northwest to southeast, likely served as the stage for the medieval market and the annual November fair. A Market Cross is marked on Ordnance Survey maps at the lane connecting the street to the church, and a rectangular Fair Green shown on the 1836 six-inch map north of the town is thought to be a post-medieval addition. Much of this history sat beneath the surface without confirmation until excavations from 2010 onwards produced extensive evidence of occupation reaching back to the later twelfth century, finally giving physical weight to what the documents had long suggested.