Ruthin Castle
It was constructed during the late 13th century by Dafydd ap Gruffydd , the brother of Prince Llywelyn ap Gruffudd , on a red sandstone ridge overlooking the valley . 
<triplet> Dafydd ap Gruffydd <subj> Llywelyn ap Gruffudd <obj> sibling <triplet> Llywelyn ap Gruffudd <subj> Dafydd ap Gruffydd <obj> sibling