Man-made underground passage in Bellasallagh

That is the largest chamber known. No exit is recorded. The chamber may have been a temple, a treasury, a workshop, a prison or a chamber for the dead. The chamber is the largest known chamber, but the function is not known. The size and the concealment suggest that the people who built it wanted to control entry. They may have measured breath, stored things, excluded witnesses or marked the boundary between the living and the dead.