OS ref 

Standing on Gelligaer common, Carn Bugail is mostly wrecked and has a triangulation point sitting rudely alongside.

There are other small cists and house platform in the area, as well as Sarn Helen, the Roman road.

More interesting is the standing stone a few hundred yards away down hill. It leans at a drunken angle, but was probably upright originally since it used to have an inscription carved in Latin. This was unfortunately defaced by a party of miners during the 1800's.

It is reputed to be erected above buried treasure but attempts to uproot the stone have all brought about disaster on the perpetrators!