In 1400, tension between the Norman lords and their imposed administration and the Welsh people and their traditional leaders exploded into rebellion. In revenge for a personal affront, Owain Glyndwr led a raid against Lord Grey of Rhuthin during which Rhuthin was razed to the ground on market day. This act rapidly led to a national uprising.

In the summer of 1401, Glyndwr led an army of 500 men to the high ground above the Afon Hyddgen and raised his standard to clash with a Norman army of 1500 men.

His success in this battle convinced many more Welsh people to join the cause. By the summer of 1404, Glyndwr was able to lay the foundations for the political order and future vision for the country. He invited 4 representatives from every cwmwd (commote or secular/non-religious division of land) to convene a senedd (parliament) at Machynlleth.

To make sure the senedd would be recognised by other countries, representatives from Scotland, France and Spain were also invited.

The Old Parliament Building stands on the site of this famous first parliament meeting. This Grade 1 listed building was restored and extended in 1911 and given to the town of Machynlleth by Lord Davies of Llandinam in February 1912.

Reference:
Interpretation and tree-ring dating by D. Miles and R. Suggett published in Vernacular Architecture, vol. 35 (2004), p. 112.
Programme of archaeological evaluation and recording by Clwyd-Powys Archaeological Trust for The Owain Glyndwr Institute reported in CPAT Report No. 674 (copy deposited in the NMRW).