The patrimonial strategies of the great lay landowners, as well as their investments in the Italian cities of the 11th-13th centuries have not been precisely studied. Until now, due to the state of the archives, historians have especially analyzed the estates and the strategies of the ecclesiastical institutions. However, some parchments from Viterbo, that can be compared with other documents from cities of Central Italy, allow us to depict the morphology of the ever-changing urban estate of the elites. Through these sources, we could assess the profitability of the different urban investments, along with the financial viability of the urban houses, whose usufruct was yielded to tenant holders. This type of investment led to create a network of clients inside the neighborhood, who could side with the great landowner in case of a feud or during a popular assembly. Finally, the family tenement was at the same time the epicenter of the urban estate, a means to make a massive investment, a way of showing the might of the landowner and of strengthening his power over his neighbors and clients. These investment strategies, which include the practice of credit, have transformed the economy, society and political life of the Italian cities. They help us to understand a period of important transition: the social and political structures of cities which had kept Carolingian features were transformed and replaced by municipal institutions.
