The purpose of this essay is to re-examine the studies on the hospital of San Nicolas in Rome, one of the health care institutions of the Crown of Aragon during the Late Middle Ages. Through the use of documentary sources, we have been able to rectify its traditional location, thought to be originally in the Corte Savella, to the << cinciana >> area of Rome. This is followed by a description the structure of the building, the identification of its origin, and the study of its successive restorations until its acquisition by Virgilio Cenci in 1518.