But the gem of this great cemetery was the cairn which we called F. This contained a magnificent chamber of unique and complicated design. It consisted of a well-built entrance passage, a polygonal chamber with recesses cut off by sills, and a second larger chamber beyond with three seperated recesses, and in this, most remarkable of all, a slender pillar-stone in the centre-line, 5 feet in height, and 7.5 by 9 inches in section.
Over this the roof rose to its greatest height, some 16 feet above the floor. The unfortunate fracture of a large slab at some bygone time had brought about a great collapse, and we had to remove tons of stuff to clear the chamber. Another accident had snapped the standing stone across, near its base, but had not impaired the sanctity which apparently was attached to it, for we found the ashes of a burnt human body laid on the butt end of the prostrate part.
The architecture of this monument was of most massive character, slabs up to four tons in weight being used in its construction; and its design, and its inner sanctuary with the standing-stone, is without parallel.
R. L. Praeger - The Way That I Went, 1937.
Cairn F greets the visitor to Carrowkeel, along with Cairn B, one on each side of the valley as they proceed up the Bricklieve Gap. Majestically located on the left cliff-top on the ridge called Carn Mór, Cairn F is the largest and most important of the cairns at Carrowkeel. It has a diameter of 26 metres and probably stood 8 - 10 metres high. It is located about 200 meters south of Cairn E at an altitude of 310 metres.
The roof had collapsed by the time Macalister arrived to excavate it and the chamber was full of cairn material. A huge lintel had cracked under the strain of the roof, allowing spalls and small stones to fall in and fill the chamber. The massive 4 ton capstone had fallen inside and lay on its edge. The work crew broke it up and removed it to make room for their excavation.
The cairn contains a very large well built chamber formed from massive squared limestone slabs, with five compartments, two at each side and an end recess. Round pieces of sandstone were used in places in an effort to relieve stress. Most interesting was the discovery of a fallen standing stone 1.5 metres long within the chamber.
Macalister estimated the original height of the corbelled roof to be 5 metres; he found this 'one of the most impressive and interesting ancient structures remaining in Ireland'. The flagstones which all came from the same quarry were trimmed and squared to a uniform shape, a characteristic trademark of the Carrowkeel builders.
The presence of a standing stone in Cairn F is very unusual and will probably prove to be of great significance is the site is ever cleared up. This pillar-stone must have broken some time before the collapse of the roof, since ashes were found spread across the stump. When and how the stone fell is a mystery; it must have cracked the sill stone of the south recess. There is a large hunk of sandstone outside the entrance to Cairn E that has been split in two. Perhaps it was broken at the same time.