This study depicts the history of the waqf endowments in Algiers dedicated to the poor of Mecca and Medina over the last 170 years of Ottoman rule. It is one of the first studies of a major public foundation based on its own registers.Its main themes are: the foundation's growth, its benefactors, the evolution of its patrimony, its administration, managerial policies and functions in the town.The author discusses the history of the foundation within two contexts - that of the Islamic endowment institution and that of the history of Algiers - and offers new insights into the interaction between the law and socio-economic circumstances, the dialogue between the local community and its rulers and the role of the foundation as a major factor in the shaping of the Algerian public sphere.