Somewhere in the townland of Greyabbey, Co. Kildare, a medieval borough once collected rents, housed tenants, and answered to the bishop of Kildare, and then, at some point in the fourteenth century, it simply stopped. No record marks its end. The place called 'Selyok' in the royal escheator's accounts, later identified by the historian Devitt as Silliothill, vanishes from the documentary record without explanation, leaving behind little more than a name and a question.

The earliest firm evidence for the settlement comes from accounts drawn up during a vacancy in the bishopric of Kildare between 1272 and 1276, when the royal escheator, the crown official responsible for managing estates during such gaps in lordship, took over administration of the see. Those accounts record £11 10s. 3d. collected in burgage rents from 'Selyok', a sum that suggests a functioning borough of some substance. A burgage was a standard unit of urban tenure in medieval Ireland and England, where townspeople held plots of land in exchange for a fixed annual rent, so the presence of burgage rents implies an organised settlement with defined plots and at least a modest population. By 1302 to 1306, the archbishop of Dublin also had possessions in the area, valued at 20 shillings a year. What happened after that is unclear. The absence of any further documentary references has led historians to conclude that the borough was probably abandoned during the fourteenth century, a period when plague, warfare, and economic contraction emptied many smaller settlements across medieval Ireland. A castle or messuage, referred to as 'the castle or messuage of Silliat', is also mentioned in connection with the settlement, though its location has never been established.

The precise footprint of the borough remains unknown. Researchers have tentatively associated it with a poorly preserved enclosure still visible in the landscape, though even that connection is speculative. It is the kind of place that rewards patient attention to the ground rather than any expectation of obvious remains.