The project was entrusted by Francesco Sforza to the Tuscan architect Antonio Averlino known as Filarete (1400-1469) and those shown it in his Treatise on Architecture as an example of public architecture in the broader context of an ideal city in which he had foreshadowed the Milan of the Sforza. The plan proposed by Filarete, based on the square, had clear references to religious symbols. The pattern behind the building is a rectangle consisting of ten equal squares among which the church is centrally located . The sides consisting of buildings with cross plan ("cruise"), as to remind the human suffering, were intended to the sicks. At the center of the "cruise" of the fifteenth century (the arms of which measure 90 meters in length 9 meters in width 9 meters in height) in correspondence of the tiburio, there was an altar which could be viewed by all. For each bed there was a small cupboard with door, which served as a table; also for the whole length of the arms of the cross were created corridors in which they were placed toilets (called "right-handed '') with futuristic solutions for the time.