This is the complex of stone settings at Pontypridd, Morganwg (Glamorganshire), known as Y Maen Chwŷf or Y Garreg Siglo (NGR:ST 08138 90098). It was built around the natural boulder, (the rocking stone), by Ieuan Myfyr and members of Cymdeithas Cymreigyddion y Maen Chwŷf, probably in 1848-1849, but some think the inner circle is earlier.
Iolo Morganwg organised the first Gorsedd of Bards in Wales here in 1795. He was present at a Gorsedd Ritual with Thomas Williams (Gwilym Morganwg, 1778-1835 landlord of the New Inn, Pontypridd from at least 1807-1835) and Taliesin (Iolo’s son) but the number of stones around the Rocking stone at those events is unknown. The site was used for many other subsequent meeting of the Gorsedd. A National Eisteddfod was held here in 1893.