The Staufer Emperor Frederick II (1194 - 1250), who ruled over the German Empire and the Kingdom of Sicily, developed a centralized state in Southern Italy that significantly influenced the history of Germany and Italy. Posterity remains fascinated by his interest in the natural sciences, philosophical and theological fundamental questions, as well as his impressive buildings, particularly Castel del Monte. His sympathy for Judaism and Islam earned him the appreciation of modern observers, though his contemporaries viewed him with very mixed feelings. Under his reign, the conflict between the Emperor and the Papacy reached its peak. Papal propaganda vilified him as a heretic and Antichrist, while he himself was celebrated as a prince of peace and messianic emperor.