A descendent of de Grey, also named Reginald, provided the spark for Owain Glyndwr's early 15th century rebellion against the English crown. De Grey and Glyndwr clashed in a minor dispute over neighbouring estates they owned near the Welsh border. The dispute escalated out of control and Glyndwr's complaint against de Grey became a general rebellion against English control in Wales. Glyndwr was proclaimed Prince of Wales, and on 16 September 1400 he attacked Ruthin and burned the town. The castle survived the attack, but in 1402 de Grey was captured and imprisoned at Dolwyddelan Castle. He was only freed after a ransom of 10,000 marks was paid.
The castle ruins consist of an upper and lower bailey. The upper bailey contains ruins of a hall, and is surrounded by partial stone walls with a twin-towered gatehouse. Little of the towers remain beyond vaulted cellars. The lower bailey has a section of wall with three towers, reached by a dry moat.
The castle, privately owned, is operated as a luxury hotel and event venue. You can book accommodation there, in fact, through our Castle Hotels in Wales section.