Indicated

On the E-facing slope of a drumlin ridge. Depicted as a circular enclosure with the designation 'Fort' on the 1837 ed. of the OS 6-inch map. A raised subcircular area (c. 26m N-S; c. 24m E-W) enclosed by a bank of earth and stone (Wth 2.5-4.6m; H 0.3-1.2m), which has been modified and incorporated into a field boundary, and a modern field drain, which almost certainly incorporates the line of an external fosse. A break (Wth 2m) in the bank at E may mark the original entrance. Compiled by: Patrick F. O'Donovan Date of upload: 26 August 2011

Derrycassan is a likely early-medieval ringfort, indicated by its circular enclosure and banked structure, situated on a drumlin slope. Local tradition may associate it with fairy lore, as with many such sites in Ireland, though specific folklore is not recorded.