This 21.5 by 20.3 metre earthwork, situated about 40 metres from the lake’s southern shore, marks the probable site of a fortified dwelling that belonged to Owen Mac Conor Og of Aghacarra in 1635. Historical records describe it as a ‘handsome dwelling house’, though today visitors will find no visible stonework from the castle itself; just the artificially flattened hilltop that once supported its foundations.

The site’s history stretches back further than the Mac Conor occupation, with records showing John Crofton held Knockroe in 1586, though local tradition more strongly associates the area with the Plunkett family. The strategic position overlooking Canbo Lough, which has since divided into separate western and eastern lakes, would have made this an ideal defensive location. About 1.2 kilometres to the east-northeast stands another fortified house at Canbo, suggesting this area held particular importance for controlling movement through the landscape.

Today, the only structural remains visible are the grass-covered foundations of a small rectangular house to the northeast, measuring roughly 4.8 by 4 metres internally with walls about 1.1 metres thick, and a short section of wall foundation to the east-southeast. These later additions likely date from after the castle’s abandonment, serving as humble reminders of the site’s continued, if diminished, occupation through the centuries.