Owain Glyndŵr's Parliament House
Owain Glyndŵr's Parliament House (Welsh: Senedd-dy Owain Glyndŵr) was traditionally the building where Owain Glyndŵr held a parliament in 1404. However, the origin of the building is probably later.
Source: Wikipedia — Owain Glyndŵr's Parliament House (CC BY-SA 4.0)