Frederick II had inherited the throne of the Kingdom of Sicily from his mother, Constance before he was two years of age. He was also Holy Roman Emperor and was said to be one of the best in the Middle Ages. Frederick II was given the nickname Stupor Mundi which means Wonder of the World because of his abilities, accomplishments, and attitudes. Frederick II was fluent in six languages, studied mathematics, philosophy, natural history, medicine and architecture, and was also a poet. Also, Frederick II ruled the Holy Roman Empire from Sicily as apposed to the heart of the empire and let wild animals roamed free, as well as welcomed Muslim scholars into those Christian territories. These talents and accomplishments are not normally what you would expect from a strong Emperor in the Middle Ages, which is why he is worthy of his nickname.
This is a map of the Kingdom of Sicily under Frederick II's control from the island of Sicily.
Above is an image of Stupor Mundi himself.