Built around 1192-3 by Geoffrey FitzRobert when he founded the town of Kells, the fortification was strategically positioned where the Kings River flows about 80 metres to the north, with a stream branching off to the west and rejoining the main river to the southeast. The bailey sits raised above the island floor, which was prone to flooding, surrounded by what was once marshland but has since been reclaimed. While the location offers excellent views along the valley floor to the east and west, the rising ground to the north and south limits visibility in those directions.

Rather than being primarily defensive, this motte served as the caput, or administrative centre, of FitzRobert’s new settlement. The site was chosen with careful consideration for medieval manorial requirements: sufficient arable land for the lord’s demesne, proximity to the river for powering the manorial mill, access to seigniorial fishing rights, and good communications links. Early 13th century charters refer to the structure as a ‘castelli’, with one document from around 1204-06 mentioning FitzRobert granting the nearby Augustinian Priory all fishing rights between his mill and the castle gate. Another charter from around 1211-12, likely issued by Geoffrey’s son William, grants the burgesses of Kells common pasture on the small island around the castle, extending to the fosse or earthwork surrounding his garden and castle, essentially the bailey and motte.

Today, only fragments of the original motte survive after much of it was destroyed in the 1980s. The remaining portions on the northeast and southeast sides suggest the motte originally had a flat top about 15 metres in diameter, built by heaping mixed subsoil and gravel five metres high atop an existing six metre glacial deposit, creating a classic pudding bowl shape with steep sides that stood 11 metres tall overall. The bailey extends westward from the motte as a raised platform defined by a scarp up to 5.2 metres wide and 1.85 metres high. The southeast and southwest boundaries of the bailey are now marked by a later bawn wall, while evidence suggests the original outer defences may have extended eastward, possibly cut through when the public road was built. This National Monument, number 626, offers a tangible connection to the Norman colonisation of Ireland and the establishment of medieval towns that would shape the island’s landscape for centuries to come.