In Lucan Demesne, where the River Griffen meets the Liffey from the east, there was once a mound, the kind of earthen construction that appears throughout the Irish landscape in many forms, from prehistoric burial mounds to later Norman mottes, which were raised earthen platforms used as foundations for timber fortifications. What exactly this mound was, when it was raised, or by whom, is no longer clear. What remains is the mention of it, and the absence where it once stood.

The sole surviving reference comes from F. E. Ball's 1906 survey, which records the discovery of a mound at the eastern confluence of the Rivers Griffen and Liffey. Beyond that single citation, the record falls silent. No dimensions are given, no description of what was found within or beneath it, no account of when or how it came to be noticed. The site was compiled as part of an archaeological inventory by Geraldine Stout, uploaded in August 2011, with the frank admission that the exact location of the monument is unknown. The Griffen is a modest stream, and the demesne itself has been shaped and reshaped over centuries of landscaping, which makes tracing any earthwork within it a considerable challenge.

Visitors to Lucan Demesne, now a public park on the western edge of Dublin, will find a pleasant stretch of the Liffey valley, but should not expect to locate any visible trace of the mound described by Ball. The confluence of the Griffen and the Liffey is findable with a little attention to the terrain, but there is nothing marked, nothing fenced off, and nothing that announces itself as the site in question. The interest here is of a different kind: the experience of standing in a landscape where something was recorded and then lost, where the archaeology exists only in the gap between an old footnote and the ground underfoot.