Tennis courts have eaten into the eastern quadrant, boulders have been dumped onto the central mound, and a row of evergreen trees has taken root along the crest of the northern bank. Whatever this place once was, it has been slowly absorbed by the ordinary business of a town expanding around it.

Enclosures of this kind, typically formed by a raised bank and sometimes a ditch, are among the most common ancient monument types in Ireland, though their precise functions vary considerably. Some were raths or ringforts, serving as enclosed farmsteads from the early medieval period; others may have had ceremonial or territorial purposes. At Killeen, the interior mound is the most conspicuous surviving feature, a roughly circular rise of earth and stones nine metres across and 1.2 metres high, sitting at the centre of the dished interior. In the south-west quadrant, the external face of the bank still stands around 0.4 metres high, though overgrowth makes any precise measurement of its width impossible. In the tree-planted northern half, a bank some six metres wide and 0.5 metres high can still be traced, though it is heavily disturbed. The site was documented by Michael Connolly as part of a survey of the Lee Valley area carried out in 1996 and 1997.

What makes the Killeen enclosure quietly striking is less what survives than how it has been accumulated upon. The large boulders piled on the central mound likely arrived during construction of the tennis courts nearby, a casual deposit that says as much about the site's invisibility to later generations as about any deliberate act. The bank, the mound, and the wide open views to the west, south, and east are all still there, partly legible beneath the trees and undergrowth, if you know where to look.