What makes it quietly absorbing is not the survival itself but the layers of time embedded within it: one circular earthwork cutting across the eastern end of an older rectangular one, each belonging to different periods entirely, stacked on top of each other in the ground like palimpsest pages.

Excavation carried out under licence 04E1604, ahead of a development project, revealed that the circular enclosure measures roughly 28 metres in diameter. Its ditch, which ranged between 5.5 and 6.2 metres wide and reached up to 1.9 metres in depth, contained twenty-six distinct fills, which in archaeological terms means the ditch was not simply dug and abandoned but accumulated material gradually across a long period of use. Scattered through a rich organic deposit within the ditch were fragments of wood including barrel hoops, a possible barrel stave, and sharpened stakes, the kind of everyday domestic and structural debris that rarely survives but speaks directly to how people lived and worked nearby. Four large postholes indicated what was likely a bridge crossing the ditch, positioned in alignment with a metalled surface, suggesting a formal and deliberate entrance route. Two radiocarbon dates were recovered from the base of the ditch: an apple wood sample returned a date of around 1010 AD, while an oak sample dated to approximately 509 AD. The five-century gap between the two has been attributed to the "old wood effect", a well-known issue in radiocarbon dating where long-lived timber gives a date reflecting when the tree grew rather than when the wood was actually used.

The eastern quadrant of the site was preserved in situ within open space as part of the development agreement, which means a portion of the enclosure remains in the ground and is not built over. Drinan itself lies in the Fingal area of north Dublin, and the site is not formally presented for visitors; there is no interpretive signage or managed access. Anyone with a serious interest in the monument would do well to consult the excavation report cited as Halliday 2008 before visiting, and to check current access arrangements locally, as the preserved area sits within what was a development zone.