The capstone is gone, leaving the chamber open to the sky, which means the interior is visible in a way that most intact megalithic tombs are not. What remains is still substantial: a chamber roughly four metres long and one and a half metres wide, running east to west, formed by two upright portal stones at the eastern end, two sidestones along the flanks, and an additional orthostat standing beside the northern portal. The whole structure sits within a cairn, the mound of stones that would originally have enclosed and supported the tomb, though its outline is irregular rather than neatly preserved. More striking still, the southern wall of the chamber has been absorbed into a field boundary, the ancient stonework pressed into service as ordinary agricultural infrastructure.

Portal tombs, sometimes called dolmens, are among the earliest monumental structures in Ireland, typically dating to the Neolithic period, roughly four to six thousand years ago. They are characterised by those paired upright portal stones at the entrance, often supporting a large capstone angled dramatically upward, and were used as collective burial chambers. The Menlough example was documented by Ruaidhrí de Valera and Seán Ó Nualláin in their 1972 survey of megalithic tombs across Ireland, a landmark catalogue that systematically mapped this class of monument across multiple counties. The proximity to Lough Corrib, one of the largest lakes in Ireland, would not have been incidental to its Neolithic builders; water, and the landscape around it, carried considerable significance in the siting of such monuments.