Carn Briw has been very seriously messed about with, by walkers and children looking for something to do......... it was probably originally a conical mound, like many other Bronze Age burial cairns in this part of the world. There has been some recent burning to the north of the cairn, and now one can see clearly the "stone takes" from which stones and rubble were taken for the original construction of the mound.
Visited 2nd May 2004: We approached Carn Briw in a straight line from Carn Ingli Camp. It's easy to spot on the horizon, but mainly because the cairn material has been seriously re-arranged. From a distance it looks like a crumpled cone.
On closer inspection the extent of the damage is obvious. One side of the cairn has been piled up high, presumably by walkers. Where the cairn remains at something like its original height an enclosure has been made in it.
Despite the mess, Carn Briw is a pleasant place to visit. It's off the beaten track for most people visiting Carn Ingli, so relatively tranquil. Also well placed for visiting the hut circles to the south west.