On its headland, where a promontory fort once enclosed a defended settlement, geophysical survey has revealed something that would be easy to walk past without knowing to look: two ring barrows lying just outside the fort's bank, and further circular anomalies concealed within. Ring barrows are a form of prehistoric funerary monument, typically consisting of a low central mound surrounded by a ditch and an outer bank, and their presence here, clustered around a promontory fort, points to a landscape that was used and reused across long stretches of time.

The evidence for these features comes not from excavation but from remote sensing. A geophysical survey carried out under Licence no. 03R0074, cited by Gabriel Cooney in 2009, first identified the two ring barrows external to the fort bank, as well as circular structures within the promontory enclosure itself. A later survey, conducted under Licence no. 12R078 by The Discovery Programme as part of the Lambay Island Archaeological Research Initiative, known as the LIARI Project, returned to the same ground and confirmed the circular anomalies previously detected. The work was compiled by Geraldine Stout and updated by Christine Baker, with records formalised at the end of 2014. What the surveys have not yet resolved is the precise date or function of the internal circular features, which remain unexcavated.

Lambay is privately owned, and access to the island is restricted, so any visit requires prior arrangement. The island has no regular ferry service open to the general public. For those with a particular interest in Irish prehistoric landscapes, the significance of the site lies less in what is visible on the surface and more in what the geophysical data implies, a layering of monument types, from funerary barrows to a defended enclosure, that suggests the headland held meaning across more than one period. The barrows themselves would appear as subtle earthwork features if visible at all, and their value at present is largely understood through the survey record rather than direct observation on the ground.