At the northern tip of Lough Arrow in Co. Sligo, between the megalithic complexes of Carrowkeel and Moytura stands one of the largest and most overlooked ancient monuments in Ireland. This is Heapstown Cairn, 'The Heap of Stone', is massive pile of stone as the name suggests. It is said to be the fourth largest cairn in the country outside Newgrange, Knowth and Dowth in the Boyne Valley, though there are several others of near the same size found in the Cong area, the site of the First Battle of Moytura. The massive kerbed cairn is quite easy to find: it is located in a field beside the road just to the north of the Heapstown cross roads by the Bo and Arrow public house.
Heapstown is estimated to measure 63 m in diameter, the largest monument in a region, which also boasts the Carrowkeel complex 8 km to the southwest, Moytura to the southeast,and Carrowmore, Knocknarea and Carns Hill 20 km to the northwest. The cairn was built on a slight rise near the northern point of Lough Arrow and is about 500 meters east of the River Uinshin. See map at the bottom of the page for location. The monument was extensively quarried in the last century; as Beranger's 1779 and Petrie 's 1837 drawings show it was originally much larger and had a standing stone on its flat summit. The mound of stone is about 12 m high at present.
Heapstown Cairn, like Maeve's Cairn on Knocknarea, has all the characteristics of a Passage Grave, though no passage or chamber were discovered during the removal of stones. The cairn is circular with a kerb of very large stones which include limestone, sandstone and igneous boulders running around the base. Where quarrying was heaviest, on the west and north east sides the kerbs are missing completely. The southeast side is least disturbed and a number of kerbstones are buried under the cairn. The cairn stones are water-rolled sandstone which are glacial deposits from the Curlew mountains at the other end of the lake, and local limestone undoubtedly quarried at a nearby outcrop. The myth says the stones came from the nearby river, the Uinshin, which flows north from Lough Arrow to Ballisodare.
From the top of Heapstown Cairn there is a fine view of the Bricklieve Mountains with several of the cairns silhouetted against the skyline. To the west is the unopened mound on Sheereevagh, located on the hill behind Ballyrush Church. Heapstown and Sheerevagh form a kind of gateway into or out of the Lough Arrow region; back in the neolithic the river was the main travelling route between Lough Arrow and Coolrea. To the south east is the Cairn of Shee Lugh on the highest point of Moytura, while to the south is Sheegorey on the eastern peak of the Curlew Mountains. Heapstown is the only cairn in the region which has no view to Knocknarea, this being blocked by a drumlin just north of the Cairn.