	The brisk building activity was continued by Philipp William's son and successor, Margrave Frederick William (1700-1771). Initially under the tutelage of his uncle Frederick (Prussian king as "Frederick I" since 1701) he ruled his dominions from 1731 onwards and began to develop Schwedt into a country seat for the cadet line. In 1734 he had married his cousin Princess Sophia Dorothea of Prussia, a sister of King Frederick the Great. As he left no male heirs upon his death, Philip William's youngest son, Frederick Henry (1709-1788) ruled as the last Margrave of Brandenburg-Schwedt and developed Schwedt into a cultural center. Known for his numerous love affairs, his marriage with Princess Leopoldine Marie of Anhalt-Dessau likewise produced no male descendants.