The place had once had, by tradition, twelve burgesses in scarlet gowns, a mayor, and all the apparatus of a functioning borough. By 1682, when Sir Henry Piers set down his description, it had become fields of excellent corn and the rubble of old walls, prompting him to compare it to the Etruscan city of Veii, so thoroughly erased that historians questioned whether it had ever existed at all. The town he was describing was Kilbixy, and it is still, in most practical senses, gone.

The place takes its name from the Irish Cill Bhiscí, the church of St Bigseach, whose early foundation preceded the Norman arrival by several centuries. After the Anglo-Norman conquest, Hugh de Lacy granted the lands to Geoffrey de Costentin, and it was probably de Costentin who raised a motte here in 1192. A motte is a raised earthen mound topped with a timber or stone fortification, the standard early Norman method of securing new territory quickly. A borough followed, and the foundation charters of nearby Tristernagh priory, granted by de Costentin between 1200 and 1224, provide a surprisingly detailed snapshot of the place: a church, a castle, a mill, a bridge, the cross of St Columba, and the house of the old Irish chaplain. There were burgages, the plots of land allocated to town settlers, recorded beside something called Carton's ditch. The settlement persisted under de Costentin family control until around the mid-fourteenth century, but as Anglo-Norman authority in the midlands contracted, Kilbixy's position became increasingly precarious. The castle appears to have been destroyed in 1285. In 1430 the town was burned by an Irish alliance under Domhnall Ó Neill. It was burned again in 1458 by the son of MacEochagain. By the 1470s, Thomas Nangle, baron of Navan, was complaining that fish from his weirs on the river Inny, the great weir and the castle weir, were being taken illegally by members of the Dalton family. After that, the documentary record falls silent.

What survives on the ground is a matter of some uncertainty, and that uncertainty is itself part of what makes Kilbixy interesting. The 1837 Ordnance Survey six-inch map marks the site of Kilbixy Town in fields roughly 250 metres south-east of the medieval church, labelling them Burgess Land. But aerial photographs taken by Cambridge University between 1966 and 1970 show an extensive spread of earthworks not in that location but in the field immediately to the west of the church, with traces extending northward as far as the motte. The earthworks focus on a triangular platform, possibly a former village green, from which three street lines radiate outward. Rectangular platforms nearby may be the footprints of houses, though they are difficult to distinguish at ground level. The field to the south-east, the one the Ordnance Survey named as the town site, shows no comparable earthwork traces on aerial imagery at all. Whether the two areas represent different phases of the same settlement, or whether the mapmakers of 1837 were simply working from faded local memory, remains unresolved.