The site, known as Tuam Seanchaidh or Tomonaghan, served as an early centre for the O'Rourke dynasty in south Leitrim and likely remained in use until the 15th century. Historical records tell us that in 1386, Aine, wife of Tiernan O'Rourke, Lord of Breifne, died here, marking the site's importance as a seat of regional authority.

The earthwork itself consists of a grass-covered area measuring approximately 36 metres from west-northwest to east-southeast and 25 metres from north-northeast to south-southwest. A substantial earthen bank, now crowned with trees and standing about a metre high, defines the perimeter. Beyond this, a rock-cut fosse or defensive ditch, ranging from 1.3 to 2 metres deep, provides additional fortification on the eastern, southern, and western sides. The canal, which follows an old section of the Woodford River, now forms the northern boundary; before this 19th-century waterway truncated the monument, the enclosure would have encompassed the entire river loop, spanning roughly 120 metres north to south.

The southwest corner features the original entrance, complete with a 4.8-metre-wide gateway and a 7-metre causeway crossing the fosse. Given its association with the O'Rourkes and its defensive features, archaeologists consider this a possible ringwork castle, a type of fortification popular in medieval Ireland. Intriguingly, records suggest a stone castle may have been constructed about 100 metres to the southeast, though a later house eventually occupied that spot. Today, the earthwork stands as one of the few surviving physical reminders of the O'Rourkes' medieval dominance in this corner of Leitrim, quietly enduring in its woodland setting between Ballymagauran Lough to the east and Gardice Lough to the west.