in a decree of the second vatican council, it was recommended that dioceses be reorganized to take into account modern developments. as part of the project begun on orders from pope john xxiii, and continued under his successors, to reduce the number of dioceses in italy and to rationalize their borders in terms of modern population changes and shortages of clergy, the diocese of ancona was united to the diocese of osimo by a decree of the sacred congregation of bishops of the papal curia, on 30 september 1986. its name was to be "archidioecesis anconitana-auximana". the seat of the diocese was to be in ancona. the former cathedral in osimo was to have the honorary title of co-cathedral, and its chapter was to be the capitulum concathedralis. there was to be only one episcopal curia, one seminary, one ecclesiastical tribunal; and all the clergy were to be incardinated in the diocese of ancona-osimo.