A ringfort, or rath, is a roughly circular enclosure defined by earthen banks and ditches, typically built as a defended farmstead during the early medieval period in Ireland. This one sat on a natural rise at Ballinahown, with a small stream curving around its northern, eastern, and southern sides, providing a ready-made boundary. To the west, an earthen bank roughly three metres wide completed the enclosure, forming a circle with a minimum diameter of around thirty metres, though much of that bank had already been worn down by the stream before anyone had a chance to study it properly.

The excavation took place in 1939, ahead of the flooding of the Blessington valley to create what is now the Poulaphouca Reservoir. The work was carried out with some urgency, as the rising water would soon make the site permanently inaccessible. What emerged from the dig was a mix of early medieval material alongside finds dating to the 18th century, suggesting the site had seen activity across a considerable span of time. There was also slight evidence for a structure somewhere near the centre of the enclosure, though the details were sparse. The findings were published by O'Connor in 1944, providing at least a partial record of a place that no longer exists in any accessible form. The flooding of the Blessington valley displaced several townlands and their associated historical features, and this ringfort is one of many sites that passed quietly out of reach when the waters rose.