Formally called the Palazzo dei Normanni, the Royal Palace of Palermo was established long ago on the site of earlier fortifications. Its earliest substantial construction dates back to the ninth century when a fortified residence existed under Arab rule. After the Normans took control of Sicily in the 11th century, they developed it into a royal residence. A major phase of construction and expansion took place under King Roger II in the early 12th century, including the addition of the famed Cappella Palatina around 1130–1132.