A topographical survey of Athlunkard, a townland in County Clare located on the bend of the River Shannon above Limerick, has revealed important evidence of a newly identified Viking fortress. The place name Athlunkard preserves reference to a ford and alongphort, a term for a defended Viking harbour that dates back to AD 840. Investigations by the National Museum and Garda some years ago into treasure-hunting activities in the Limerick area led to the discovery of earthworks in the townland of Fairyhill, near Athlunkard Bridge. A recent survey of the site gathered detailed topological data, which were computer processed to generate a three-dimensional topographic image of the earthworks. The survey delineated a site defined by an L-shaped ditch backing onto the Shannon, with the main river forming the southern boundary and a small tributary marking the western edge. A roughly D-shaped enclosure (75m by 30m) surrounds an oval, flat-topped mound (22m by 12m) that survives 0.4m above the surface. The enclosure enjoys natural protection, being located on poor marshy ground, with bog land and a stream forming its landfall. The survey also revealed a small oval mound 25m to the north-east of the enclosure. The earthworks are believed to date to between 840 and 930.