A quiet road runs through the small Kildare village of Rathmore, with long, narrow plots of land stretching away from the main street in a pattern that most passers-by would never think to question. But those strip-like divisions are not random. They are almost certainly the fossilised outlines of medieval burgages, the standardised land parcels allocated to settler townspeople in Norman-era planned boroughs. The fact that a functioning medieval town once occupied this ground, and that its layout may still be readable in the fields and earthworks around the village, is the kind of detail that tends to get quietly swallowed by the landscape.

The name itself points to an older layer still. Rathmore derives from 'Rath Mhór', meaning 'the big fort', though whether this referred to the motte, the raised earthen mound that formed the core of an early Norman fortification, or to an even earlier ringfort on the same ground, remains uncertain. Prince John, in a document dated between 1185 and 1189, confirmed the grant of the place to Gerald Fitzgerald, an ancestor of the Fitzgerald barons of Offaly and later earls of Kildare, and threw in the right to hold a weekly market for good measure. By 1203, Gerald Fitzmaurice had gone further, granting a borough charter, and around 1220 his son Maurice confirmed the burgesses' rights under the liberties of Breteuil, a standard package of Norman urban privileges, while laying out 96 burgages at an annual rent of twelve pence each. Eighty-five of those plots were to contain seven acres and a frontage; eleven were smaller, at half an acre. By 1331 the settlement was generating £19 in rents for Richard FitzThomas, earl of Kildare, suggesting a reasonably active community. But its position on the colonial frontier was precarious. In 1355 and 1356, Maurice Fitzgerald, earl of Kildare, received a royal order to station himself at Rathmore in person, with five mounted men-at-arms, twelve hobelars (lightly armed cavalry), forty archers, and additional foot soldiers, to hold the line against the O'Broin and their allies. The borough seems to have faded after the fourteenth century, though a provost named Tirlagh Doyne was still recorded in 1608. Before that, the place had been burned by Rory Og O'More, who died in 1577, and partly burned again by the O'Byrnes in 1580. By 1654 the Civil Survey recorded a manor house or castle, three further castles, and a mill at Rathmore, all of them described as waste, their precise locations now lost, with the exception of Segrave's Castle.

Some traces of the medieval borough may still be visible on the ground. Low earthworks to the northwest of the road between the motte and Segrave's Castle may represent further burgage boundaries, and the wide, grassy track that runs parallel to Main Street, documented on a seventeenth-century map of the village, gives a sense of where a second medieval street once ran. Walking the main street with this in mind, the long rearward plots that survive between it and that old trackway take on a different quality; less agricultural accident, more the stubborn persistence of a planned town that has otherwise almost entirely disappeared.