This earthwork fortification, likely constructed by the Anglo-Normans in the late 12th or early 13th century, consists of a raised earthen mound, or motte, which would have originally supported a wooden tower, alongside a lower enclosed courtyard known as a bailey. The strategic placement of this castle allowed its occupants to survey the surrounding landscape whilst maintaining a defensive advantage over any approaching threats.

The motte at Carrownlough rises approximately 10 metres high, its steep sides still clearly defined despite centuries of weathering. The adjacent bailey, partially enclosed by earthen banks and ditches, would have housed the everyday buildings of the castle complex; stables, workshops, and living quarters for the garrison. Archaeological evidence suggests this site may have been occupied for only a relatively short period, possibly abandoned as stone castles became more prevalent throughout Ireland in the 13th and 14th centuries.

Today, the site stands as a monument to the Norman conquest of Connacht, when families like the de Burgos and de Berminghams carved out lordships in the west of Ireland. Local folklore tells of underground passages connecting the motte to nearby holy wells, though no archaeological evidence supports these tales. The earthworks remain remarkably well preserved, offering visitors a chance to walk the same defensive perimeter that medieval soldiers once patrolled, and to imagine the wooden palisades and towers that once crowned these now grass-covered mounds.