The circle was erected at Parc y Dyffryn, Aberpennar in 1904 for the 1905 National Eisteddfod, and reused to proclaim the 1940 Eisteddfod which was then cancelled due to the Second World War.

A circle of 12 stones within an outer circle of 19 stones; three external stones on the same radii as the three stones on the east side of each circle.

"At a meeting of the Gorsedd Committee this week it was announced that the Gorsedd circle, which is built entirely of unhewn stones of large size brought from the side of the mountain, was finished. It had been pronounced by some of the highest authorities as one of the finest Gorsedds of recent years, and the site in the centre of a handsome grove of oak trees is admirable. It stands on the centre of a natural amphitheatre, which lends itself to the ceremony, as it will be visible from either side. The date has been fixed for July 16th, and the invitation to the ceremony has accepted by most of the neighbouring councils and corporations. The procession will leave the pavilion, where some twelve months later the Eisteddfod itself will be held, at three o’clock, and will proceed to the Gorsedd along Oxford street and Aberdare Road, past the vicarage to the Gorsedd, and at the close of the ceremony the procession will return to the Workmen’s Hall, where a luncheon will be partaken of". Cardiff Times, 2 July 1904

Reference: information from research into Gorsedd Circles carried out by Michael Freeman between 2005-2024.