bailey were falling down. In 1404, Owain Glyndŵr captured and took possession of the castle during a national uprising against English occupation. There would be a treaty signed between Glyndŵr & the King of France at the Castle. Four years later, it was retaken by the English, and became an important seat of the government. In 1637 Charles I turned the castle into a Royal mint, and it became a producer of silver shillings. The mint's operator raised a regiment of Royalist soldiers during the English Civil War. The mint closed down during the Civil War, but served as a warehouse for storing silver and lead. Oliver Cromwell slighted the castle in 1649. Architecture Building work started in 1277 at the time of the First Welsh War, the work begun during Edward I's first Welsh campaign at the same time as work started at Flint, Rhuddlan and Builth Wells. The inner ward was built in a diamond-shaped concentric castle, with a twin D-shaped gatehouse keep and mural towers at each corner. The outer ward is described as consisting of a "twin D-shaped gatehouse, a barbican, a rock-cut ditch and a large curtain wall with towers". See also Ring of Iron Castles in Great Britain and Ireland List of castles in Wales References External links Castles in Ceredigion 1277 establishments in Europe Buildings and structures in Aberystwyth Castle ruins in Wales Grade I listed castles in Wales Grade I listed buildings in Ceredigion 13th-century establishments in Wales