Pembroke Castle (Welsh: Castell Penfro) is a medieval castle in Pembroke, West Wales. Standing beside the River Cleddau, it underwent major restoration work in the early 20th century. The castle was the original seat of the Earldom of Pembroke.
In 1093 Roger of Montgomery built the first castle at the site when he fortified the promontory during the Norman invasion of Wales. A century later this castle was given to William Marshal by Richard I. Marshall, who would become one of the most powerful men in 12th-Century Britain, rebuilt Pembroke in stone creating most of the structure that remains today.
More information on the Wikipedia page [1]