In the history of tourism in Italy, the First World War represented a moment of profound transformations in the structure of investments in tourist services and in accommodation. After the national unification and the proclamation of the Kingdom of Italy (1861), the Italian peninsula, already very attractive for European and American tourism, had also become more accessible and interesting for foreign investors, who actively participated in the expansive and liberal phase of the early twentieth century. The outbreak of the First World War interrupted many economic circuits and cultural and professional relationships. This chapter seeks to analyse two important phenomena. The first is the interruption of the flow of foreign capital—Swiss, French, and Belgian—invested in the grand hotels of the cities of art and spa towns in Italy. The second is the interruption of economic relations in the tourist services of Bolzano and Trento, when these two provinces, following the treaties of Paris, passed from the Austro-Hungarian Empire to the Kingdom of Italy.