What an odd little place this is. The sign at the gate says 'Clonlum South Passage Tomb', but it isn't really a passage tomb. It does have some passage tomb features, but that doesn't make it one.

The remains of the mound (why is it marked as 'Cairn' on the OS map) is about 1.5m high and edged by a kerb of large boulders. As you approach across the field you can see some stones protruding above the centre of the flattened top. These are the remains of the chamber. Where's the passage?

The chamber is more like a small portal tomb than a passage tomb. It is a small box like chamber with a backstone and two orthostatic sides. A doorstone, set between two other stones (portals?) blocks the west end.

This really is an enigma as far as classifictaion goes, but it's quite sweet.