The western enclosure, partially cut through by a modern road, is defined by steep scarps with a raised bank along its northern edge, measuring approximately 67 metres from north-northeast to south-southwest and 62 metres from west-northwest to east-southeast. An external fosse, or defensive ditch, runs around the perimeter, with the main entrance positioned at the southern end.

The eastern enclosure mirrors its western counterpart in many ways, featuring similar defensive scarps and banks along its northern side. This section measures about 70 metres from west-northwest to east-southeast and 52 metres from north-northwest to east-southeast. The two enclosures share a substantial 12-metre-wide fosse along their adjoining boundary, suggesting they may have functioned as a single defensive complex. The eastern site has its primary entrance on the western side, with what appears to be a secondary entrance to the south, where an additional outer bank provides extra fortification.

A stream flows to the south of both enclosures, which would have provided a natural water source for the medieval inhabitants whilst adding another layer of defence to the site. These moated sites, common throughout the Irish midlands, typically date from the 13th to 14th centuries and were often associated with Anglo-Norman settlement patterns, though some were also adopted by Gaelic Irish families. The dual nature of the Brownstown site, with its shared defensive features, suggests it may have housed an extended family group or served multiple functions within the medieval landscape.