Iranian cities witnessed a growing enthusiasm for the construction of public buildings during the fifteenth century. These constructions were called the ‌beqāʿ al-khair (houses of charity). The patronage of construction and repairing the ‌beqāʿ al-khair during this century was not only by the central government but also by other individuals. This caused a significant increase in the number of the beqāʿ in both urban and suburban areas. The economic ends for this type of building has been studied previously, but there were other purposes as well. The present paper aims to show why there was a surge in building them during the fifteenth century and how they affected Iranian cities. Through a historical approach and analysis and discussion of evidence from primary sources (such as histories, local histories, endowment deeds, and tadhkirahs), the study shows that the beqāʿ al-khair were often unsustainable foundations, and that, in most cases, their period of prosperity did not last beyond the lifetime of their founders. Nevertheless, they embodied the prosperity of the city and the justice of their rulers. Despite their short-lived prospering period, the beqāʿ al-khair were important institutions in that they were deemed as symbols indicating the flourishing of a city, and the justice of its rulers. It is argued that the reason for this significance should be sought in the role of the ‌beqāʿ in the social and economic life of the cities. The ‌beqāʿ financially supported three different classes: the patrons (sponsors), the ‘ulama (scholars), and the poor. The construction of these buildings was probably aimed to fulfill a combination of material and spiritual ends. The extent of their influence on Iranian cities was such that one cannot fully comprehend the structure of a fifteenth-century city without knowing of its ‌beqāʿ al-khair.