Pembroke Castle 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. n 1189, Pembroke Castle was acquired by William Marshal. The Earl Marshal then set about turning the earth and wood fort into an impressive Norman stone castle. The inner ward, which was constructed first, contains the huge round keep with its domed roof. Its original first-floor entrance was through an external stairwell. Inside, a spiral stairwell connected its four stories. The keep's domed roof also has several putlog holes that supported a wooden fighting-platform. If the castle was attacked, the hoarding allowed defenders to go out beyond the keep's massive walls above the heads of the attackers. Although Pembroke Castle is a Norman-style enclosure castle with great keep, it can be more accurately described as a linear fortification because it was built on a rock promontory surrounded by water. This meant that attacking forces could only assault a narrow front. Architecturally, Pembroke's thickest walls and towers are all concentrated on its landward side facing the town, the river creating a natural defense around the rest of its perimeter.