No house in France better reflects the magical promise of 20th-century architecture than the Maison de Verre. Tucked behind the solemn porte-cochere of a traditional French residence on Rue Saint-Guillaume, a quiet street in a wealthy Left Bank neighborhood, the 1932 house designed by Pierre Chareau challenges our assumptions about the nature of Modernism. For architects it represents the road not taken: a lyrical machine whose theatricality is the antithesis of the dry functionalist aesthetic that reigned through much of the 20th century.