Rationalism is an architectural movement mainly developed in Italy in the 1920s and 1930s. Vitruvius claimed in his work “De architectura” that architecture is a science that can be comprehended rationally. Twentieth-century Rationalism derived less from a unique, unified theoretical work than from a common belief that the most varied problems posed by the world could be resolved by reason. In that respect, it represented a reaction to Historicism and contrasted with Art Nouveau and Expressionism.