This roughly circular enclosure, defined by an earth and stone bank with an outer fosse and second bank, offers commanding views across the surrounding pastureland. The site appears on the 1640 Down Survey map as a tower house castle belonging to John Dillon, listed as an ‘Irish papist’, whilst the 1837 Ordnance Survey depicts it as a circular enclosure containing two buildings, one mysteriously labelled ‘Sterns Folly’. Archaeological surveys from the 1970s revealed stone foundations in the northeast quadrant that may be the remains of the original tower house, along with a mound in the eastern section topped by stone ruins that could be the folly itself.

The site’s history stretches back considerably further than its medieval castle phase. Local tradition, recorded by the Ordnance Survey in 1837, identifies this location as ‘Bruighean da Choga’ or ‘Da Choga’s Hostel’, an ancient hospitality site dating to around 600 AD that served travellers on the route between Ballymore and Athlone. The earthwork measured 204 paces in circumference when surveyed in the 19th century, and elderly locals at that time recalled seeing substantial portions of the castle still standing in their fathers’ day, when it had been repurposed as a renowned ball alley that attracted players from Ireland, England and America.

What makes The Breen particularly fascinating is its layers of reuse across centuries; a possible pre-Norman earthwork that was fortified with a stone castle during the medieval period, which then became a landscape feature or folly for the Stearne family after 1700. Today, this bivallate enclosure remains well preserved within a larger field system defined by what may be medieval field boundaries, visible as banks on modern aerial photographs. The entrance gap at the south-southeast still marks the original access point, whilst the remains of a small house site can be traced just outside the monument to the southeast, along with traces of an old road preserved in the field boundary 80 metres to the south.