Economic historians call the era from about 1475 to 1630 the "beautiful 16th century" because of the return of peace, prosperity and optimism across the nation, and the steady growth of population. Paris, for example, flourished as never before, as its population rose to 200,000 by 1550. In Toulouse the Renaissance of the 16th century brought wealth that transformed the architecture of the town, such as building of the great aristocratic houses. In 1559, Henri II of France signed (with the approval of Ferdinand I, Holy Roman Emperor) two treaties (Peace of Cateau-Cambrésis): one with Elizabeth I of England and one with Philip II of Spain. This ended long-lasting conflicts between France, England and Spain.