Yet just inside that entrance, on a natural ridge above the Liffey Valley, sits a flat slab resting on two boulders set into concrete, all that remains of a cemetery mound that was already ancient when the park's walls were being built. The stones have small holes pitted across their faces, their purpose unclear, and the whole structure has the look of something easily walked past without a second glance. The site carries the old Irish name Cnoc-Maraidhe, meaning Hill of the Mariners, though what that name preserves, whether a memory of river-watchers or something older still, is not recorded.

Sometime in the early nineteenth century, excavations opened the mound and found the central cist, a type of stone-lined grave box, containing two crouched skeletons. Alongside them were a shell necklace, a flint knife, and a bone toggle, objects that together suggest a burial of some deliberate care. Four smaller satellite cists were also uncovered, holding cremated bones and food vessels, two of which were bowls. The finds were recorded by Wood-Martin in 1895 and subsequently studied by John Waddell, whose work on Irish Neolithic burial practices helped place the site within a recognised category. Scholars Ryan, Brindley, and Lanting classified it as a Linkardstown-type burial, a Late Neolithic tradition named after a comparable site in Co. Carlow, in which a central inhumation beneath a round mound is sometimes accompanied by satellite cremations. The dating places this monument roughly five thousand years ago.

The surviving cist stands inside the Chapelizod gate, on the ridge running roughly parallel to the Liffey. Because it sits within Phoenix Park, access is straightforward and free during park opening hours, though the monument itself is easy to overlook without a little preparation. It is worth knowing in advance exactly what you are looking for: a low, modest arrangement of stones that reads, at first glance, as little more than a landscaping feature. The holes in the stone faces reward a closer look. There are no information panels on site, so arriving with some background, perhaps the work of Geraldine Stout, who compiled the archaeological record for this entry, will make the visit considerably more legible.