In 2011 Italy celebrated its 150 years of national unity. Notoriously, the stages of this history are: the liberal State (1861-1922), the fascism (1922-1943) and the democratic republic (from 1943-1946 on). The partial continuities that exist between these different stages and with the long past of the country are overwhelmed by the differences. This study analyzes the characteristics of each period and shows the principal features and the great values of the constitutional State founded by the constituent assembly of 1946-48. it describes the events of the rich although difficult implementation of the constitution during the six decades after its enforcement and stresses the present crisis and the strong resistance affecting the constitutional State, proposing a deeper "republican faith" as the spiritual solution of this crisis.