The Camerlengo of the Holy Roman Church is the administrator of the property and the revenues of the Holy See, and as such is successor both of the Archdeacon of Rome and of the Vicedominus, the former of whom administered the property of the entire Roman Church, i.e. the Diocese of Rome, while the latter was especially charged with the administration of the mensa of the pope and the entire personnel of the patriarchium Lateranense (St. John Lateran).
Thank you for reading this post, don't forget to subscribe!This latter official was the same as the syncellus at Constantinople. The office of Archdeacon of Rome was suppressed by Gregory VII, himself its last incumbent under Alexander II; owing to its numerous ancient privileges and rights it had come to be a frequent hindrance to independent papal action. When these were lopped off, the (Roman) office of arch-deacon shrank to its original proportions. Thereafter the cardinal to whom was committed the supervision of the Camera Apostolica (a term even then customary for the administration of the temporalities of the Holy See) was known as Camerarius or, in popular language, Camerlengo. The subordinates of this official are known as clerks (chierici) of the Camera; chief among them are the treasurer and the auditor di Camera. Their body is known as Reverenda Camera Apostolica (see APOSTOLIC CAMERA). When the cardinal-camerlengo happened to be absent on some pontifical business, a vice-camerlengo was chosen in his place. The office of camerlengo included not only the supervision of the immediate properties of the Holy See, but also the fiscal administration of the Pontifical States, the Patrimonium Petri.