This rectangular enclosure, measuring approximately 38.5 metres from northwest to southeast and 30 metres along its western side, is defined by a substantial clay bank that rises 1.3 metres on its exterior face. The bank itself spans three metres in width, though centuries of weathering and agricultural use have reduced its western section to a mere scarp. Historical Ordnance Survey maps from 1843 show the site as a rectangular outline with its southern edge meeting a field boundary, whilst the 1904 edition depicts what appears to be a pit feature within the enclosure.

Today, the site serves as a small field and shows considerable disturbance from its long history of agricultural use. The enclosing bank has been breached in several places; cattle have trampled a gap at the southern end of the eastern side, whilst another opening at the eastern end of the south side provides access to the neighbouring field. A third gap in the centre of the western side has been created by cattle seeking access to two feeding troughs that now occupy the interior space.

The site represents a typical medieval moated settlement, a type of fortified farmstead that became popular in Ireland during the Anglo-Norman period. These earthwork enclosures, surrounded by water-filled ditches and banks, provided both defence and status for their inhabitants, usually prosperous farmers or minor landowners. Though the moat itself is no longer water-filled and the banks have suffered from centuries of use, the Millbrook site remains a tangible link to the medieval landscape of North Tipperary.