Visited 29.10.10 and Postman was right, its huge and on first sight (without any previous knowledge) you may not think it actually is a barrow. Its sits on land directly opposite a farmhouse of the same name.
It shows signs of abuse and is very pitted and eroded, but well worth a visit. I hopped over the gate and into the ‘paddock’ in which the barrow is sited. The ‘paddock’ is clearly a rectangular walled enclosure but probably only several hundred years old. It appears to be a walled field whose drystone walls have tumbled and are now covered in earth, moss, etc. The barrow is neatly framed in the centre of this field enclosure.
The views in all directions are that of distant hills and mountains and Rhiwiau appears to sit in the bottom of a bowl whose sides are those distant hills – no coincidence I guess?!