Carn Fawr represents the last site visit of my day... and, furthermore, could well be the most isolated cairn upon the whole of the Pumlumon massif. You can take it as a given, then, that the vibe and 'sense of place' here makes the receptive traveller feel 'on top of the world'. In a manner of speaking, of course, since this cairn is actually located just below the 2,000ft contour. But truly that is of little relevance here.
According to Coflein [see misc post] there are actually the remains of two further Bronze Age cairns upon this craggy hilltop overlooking Cwm Hengwm, the upper reaches of which are, incidentally, cited by experienced climbing author Dave Ing as the 'wildest cwm in all Wales'. I have to admit, however, that the potent combination of Carn Fawr's impressive dimensions and the manner in which it relates to the landscape renders the memory defective in this instance. Yeah, there can be only one. Carn Fawr not only lives up to its prosaic name... 'Big Cairn'... but additionally has no trouble at all picking the lock of the door to the human psyche labelled 'folk memory, cairns, pertaining to fascination of'. In short, it just looks 'right', you know?
It is therefore sad to relate that Carn Fawr - the large one, that is (the baton is passed to other TMA members to add detail of the others) - has, despite initial appearances, not survived the passage of time as well as its two great neighbours upon Cwmbiga, having a somewhat hollow core. Nonetheless there is a lot of stone within this great stone pile, although, having said that, it is the location which really makes this a 'must visit' for the Citizen Cairn'd on walkabout upon Pumlumon. Situated just a little to the north of the source of the Hafren (Severn) and with Carn Hyddgen, rising across Cwm Hengwm, just one of numerous similarly blessed hills nearby, this is a spot to truly lose yourself for a while. Just make sure it's only in a metaphorical sense, please! Map, compass and the usual kit are, needless to say, essential. But I've said it anyway.
If approaching from Carnfachbugeilyn... Carn Fawr is actually visible from the former looking to the approx west. Follow the fence line to the approx south-west before striking off downhill to your right. If you lose sight of the cairn, carry on until the fence line swings sharply to your left (south)... the monument is now below to your right (approx north).
Finally, thanks to Derfel for posting the images which prove local knowledge cannot really be surpassed.
Three Bronze Age cairns stand near the north-western extremity of the main Pumlumon ridge, west of Carnfachbugeilyn and a little north of the source of The River Severn (Afon Hafren). Coflein has quite a bit to say, thanks to J.J. Hall:
Carn Fawr 1) - SN8181090530 - 'A Bronze Age stone cairn, 11m in diameter and 2m high, on a northwest facing false crest. The interior had been hollowed out to create a shelter. A linear arrangement stones, about 4m long east-west, led off from the western side of the cairn. Only one block of quartz could be seen in the cairn, which was thought to be of note as there was a lot of surface quartz in the area. When the feature was recorded in August 2006, there was no vegetation on the cairn. J.J. Hall, Trysor, 14 November 2006.'
Carn Fawr 2) - SN8186590580 - 'A small stone cairn, 3m in diameter and 0.5m high, utilising an outcrop. Some signs of structure were apparent. When the feature was recorded in August 2006, it was partially covered in grass and bilberries. J.J. Hall, Trysor, 9 September 2006'
Carn Fawr 3) SN8182090545 - 'A low, stone cairn, 2m in diameter and 0.1m high, 10m northeast. When the feature was recorded in August 2006, the cairn had grass and bilberries growing on it. J.J. Hall, Trysor, 9 September 2006'