The Diocese of Arezzo-Cortona-Sansepolcro () is a Latin diocese of the Catholic Church. It has existed since 1986. In that year the historic diocese of Arezzo was combined with the diocese of Cortona and the diocese of Sansepolcro, the enlarged diocese being suffragan of the archdiocese of Florence.

History Arezzo was the see of a diocese in Tuscany, directly dependent on the Holy See. Tradition says it was converted in the 1st century by Romulus of Fiesole, afterwards Bishop of Fiesole, a disciple of St. Paul. Another foundation tale has it that Christianity was brought to Arezzo by S. Barnabas, and by S. Timothy, the disciple of S. Paul.Pasqui I, p. vi: E una semplice credenza, non avvalorata da prova diretta, ma potrebbe riferirsi al fatto che nella espansione del cristianesimo in Toscana avessero avuta parte gli apostoli venuti dalla Grecia anzicbè da Roma. An equally implausible claim is that all of Arezzo was baptized during the episcopacy of Bishop Dicentius in the 5th century.Life of Saint Gaudentius, quoted in Lanzoni, pp. 571-572.

The city's clerks often helped build the church in their own free time. The church helped reward these people with seats of Cardinals. Many of the seats are still there with the names of people who had helped build and donated to the church.

It became a bishopric about 304, under Saint Satyrus. Saint Donatus, his successor, is patron of Arezzo Cathedral, also dedicated to Saint Peter the Apostle. The diocese was originally very large, embracing most of southeastern Tuscany. In 1325, however, Pope John XXII created the diocese of Cortona out of the territory of Arezzo. In 1462, Pius II created the dioceses of Pienza and Montalcino. In 1561, Pius IV created the diocese of Montepulciano. In 1515 (1520), Leo X created the diocese of Borgo San Sepolcro.Kehr III, p. 145.

The Canons were gathered together as a corporation by Bishop Petrus, c. 840, on instructions from the Emperor Lothair.Pasqui I, p. 44, no. 30. Kehr III, p. 157. Colleges of Canons were being created at cathedrals in accordance with the French Council of Aquisgrada (816) and the Roman council of Pope Eugene II (826). J.-D. Mansi (ed.), Sacrorum Conciliorum nova et amplissima collectio, editio novissima, Tomus XIV (Venice: A. Zatta 1769), p. 233-234; 1003-1004. Bishop Helmpertus built new quarters for them in 1009.Pasqui I, p. 129-131, no. 94: "igitur quoniam domum pro necessitatis qualitate cum suo claustro fieri precepi. et fratres in ea ad statuta canonica observanda elegi, ut meo tempore illius domns et fratrum facultates in augmentum venirent penitus necessarium esse previdi." In 1677, the cathedral Chapter was composed of four dignities (the Provost, the Archdeacon, the Dean, and the Primicerius) and fourteen Canons.Ritzler-Sefrin V, p. 97, note 1.

Bishop Theodaldus (1023–1036?) invited Guido of Arezzo to train the cathedral singers in the plainchant. He dedicated his book Micrologus to Bishop Thedaldus c. 1025. A letter of Guido to Bishop Theodaldus survives, in which he explains his methodology.

Between 1480 and 1485, Luca Pacioli, O.Min., a native of Borgo San Sepolcro, which is a distance of 16 miles (25 km) from Arezzo, visited the site, and described it as "utterly stunning."

While Cardinal Guadagni was Bishop of Arezzo, he was able to obtain from his uncle, Pope Clement XII, a number of privileges for himself and Arezzo. In the bull "Insignes Ecclesias" of 1 November 1737, Pope Clement lauded the antiquity, faithfulness, and prestige of the diocese as a direct subject of the Roman Church, and conceded to its bishop in perpetuo archiepiscopal insignia, the pallium (which could only be worn inside the diocese, and on certain specified feasts and holy days) and the patriarchal cross.Cappelletti XVIII, pp. 153-159.

Reorganization of the diocese On 18 February 1984, the Vatican and the Italian State signed a new and revised concordat. Based on the revisions, a set of Normae was issued by the Vatican on 15 November 1984, which was accompanied in the next year, on 3 June 1985, by enabling legislation. According to the agreement, the practice of having one bishop govern two separate dioceses at the same time, aeque personaliter, was abolished. Instead, the Vatican continued consultations which had begun under Pope John XXIII for the merging of small dioceses, especially those with personnel and financial problems, into one combined diocese. In Tuscany, this particularly affected three dioceses: Arezzo, Cortona, and Borgo San Sepolcro (Biturgensis).

On 30 September 1986, Pope John Paul II ordered that the dioceses of Arezzo, Cortona, and San Sepolcro be merged into one diocese with one bishop, with the Latin title Dioecesis Arretina-Cortonensis-Biturgensis. The seat of the diocese was to be in Arezzo, and the cathedral of Arezzo was to serve as the cathedral of the merged diocese. The cathedrals in Cortona and San Sepolcro were to become co-cathedrals, and their cathedral Chapters were to be a Capitulum Concathedralis. There was to be only one diocesan Tribunal, in Arezzo, and likewise one seminary, one College of Consultors, and one Priests' Council. The territory of the new diocese was to include the territory of the former dioceses of Cortona and Borgo San Sepolcro.Acta Apostolicae Sedis 79 (Città del Vaticano 1987), pp. 654-656.

Bishops of Arezzo to 1000

SatyrusSatirus lived under Pope Julius I (337–352), according to the Passio Donati. Hofmeister, MGH XXX, p. 1439, with note 3. Lanzoni, p. 569. Pope Clement XII's bull "Insignes Ecclesias" states that Satyrus was the first bishop of Arezzo: Cappelletti, p. 154. Donatus (d. 362 ?)In some hagiographical texts he is called a "confessor", in others a "martyr". His end is attributed to the persecution under Julian the Apostate (361–363), on 7 August 362, though there is no evidence for such a prosecution in the western half of the Empire. Lanzoni, pp. 569-570. GelasiusBishop Gelasius, according to an Arretine chronicle of the 11th century, constructed a small oratory. His name is found in the Passio S. Gaudentii, a hagiographical work. Lanzoni, pp. 570-571. DomitianusThis name is only found in a list of bishops of Arezzo, the earliest of which was compiled on orders of Gerardus, Primicerius of the church of Arezzo in the third quarter of the 11th century. Dates are unknown. Lnazoni, p. 571. Hofmeister, MGH XXX, p. 1438, 1439. Severinus Florentius Maximianus Eusebius GaudentiusLanzoni, p. 571-572, attributes Gaudentius to the second half of the 5th century, noting that the material concerning him is hagiographical in nature. DicentiusDicentius is mentioned only in the Passio S. Gaudentii: Lanzoni, p. 572. LaurentiusHis name is found in the Vita S. Floridi of the 11th century or later, derived from the "Life of S. Ambrose of Milan". Lanzoni, p. 572. Gallius (Gallus)This name is only found in a list of bishops of Arezzo, the earliest of which was compiled on orders of Gerardus, Primicerius of the church of Arezzo in the third quarter of the 11th century. Dates are unknown. Lnazoni, p. 572-573. Hofmeister, MGH XXX, p. 1439. Benedictus Olibrius Vindicianus Cassianus Dativus Dulcitius Innocentius Maiurianus Servandus (c. 650)Bishop Servandus entered into an agreement with Bishop Maurus of Siena (c. 635–649). Pasqui, pp. 4-5. Cyprianus (attested 680)Bishop Cyprianus was present at the Roman synod of Pope Agatho in 680. J. D. Mansi (ed.), Sacrorum Conciliorum nova et amplissima collectio, editio novissima, Tomus XI (Florence: A. Zatta 1765), p. 775. Lanzoni, p. 573. BonushomoPasqui I, p. 9, 10, 14, 16: Et interrogavimus eum: Te quis sacravit presbiterum?‘ Respondit: Bonushomo episcopus ecclesiae aretino; ipse me consecravit, et manu mea in sancto Donato feci, et sacramentum secundum consuetudinem ibidem prebui. Vitalianus Alparius Lupartianus (attested 714, 715)Pasqui I, pp. 6-24, nos 4-7. Deodatus Aliseus (c. 735 ?)Pasqui I, p. 24, no. 8. Stabilis CunimundusBougard, p. 63, assigns him the dates c. 753–782. Aribertus (attested 801)Pasqui I, p. 32, no. 19. Bougard, p. 63, assigns him the dates c. 783–805. Lampertus (819–828)according to Bougard, p. 64. He was one of sixty bishops who attended Pope Eugenius II's Roman synod of 826. Petrus (c. 833–843)Bougard, pp. 64-65, 68. Petrus Ioannes (c. 863–900)Bougard, p. 65-67. Petrus (900–916)Bougard, p. 67. Theodicius

... Hugo (attested 952)Bishop Hugo was present at the Reichstag in Augsburg, held on 7 August 952. Schwartz, p. 199. Everardus (attested 963–979)Everardus was a Frank, the son of Margrave Boniface of Spoleto and Camerino. Schwartz, pp. 199-200. Helmpertus (attested 994–1010)Helmpertus carried out resconstruction work on the cathedral: Bougard, p. 68. Schwartz, p. 200.

1000 to 1500

Willelmus (attested 1011−1013)Schwartz, p. 200, speculates that he is the Wilelmus who was the Archdeacon of Arezzo in 996–1009. He was the son of Zenovius who had a brother Griffo and two other deceased brothers, Ugo and Eribert. Adalbertus (attested 1015–1021)Adalbertus had been archbishop of Ravenna, but was expelled from that See in 1014 by the Emperor Henry II. Schwartz, p. 200. Teodaldus (attested 1023–1033)Bishop Teodaldus was the son of Margrave Teodaldus of Canossa, and thus paternal uncle of Matilda of Tuscany. Ughelli I, p. 415. Schwartz, pp. 200-201. Irenfridus (Immo) (attested 1036–1048)A Frank, Irmenfredus had been deacon of Worms. Ughelli I, p. 415-416. Schwartz, p. 201. Arnaldus (attested c. 1051−1060)Arnaldus was granted a privilege by Pope Stephen IX on 19 November 1057. In May 1059, he was present at the Roman synod of Pope Nicholas II, and had a case heard against the Bishop of Siena. Ughelli I, p. 416. Kehr III, p. 151, no. 25. Schwartz, p. 201. Constantinus (attested 1063–1095)On 8 June 1070, Pope Alexander II, who was visiting Arezzo, confirmed the diocese's privileges and territory for Bishop Constantine. Constantine took part in the enthronement of Guibert of Ravenna as Antipope Clement III in June 1080. He was excommunicated for his rash action, and, according to Archbishop Gebehard of Salzburg, he was still under the ban in 1084. Ughelli I, pp. 416-417. Schwartz, p. 201-202. Kehr III, p. 151, no. 27. Sigifredus (attested 1099)Sigifredus: Schwartz, p. 202. Gregorius (Gualterius) (1105−1114)According to testimony given by a parish priest of Arezzo in 1177, Bishop Gualterius was summoned to Rome, tried on a charge of "incest" by Pope Calixtus, and deposed (coram papa calixto de crimine fuit accusatus incesti; deinde convinctus, ab ipso domino papa depositus fuit). Pasqui I, p. 520, who points out the chronological impossibility of Pope Calixtus being involved. Guido Buccatoria (1114–1128)On 17 November 1115, Pope Paschal II confirmed for Bishop Guido the privileges previously granted by earlier popes. In March 1124, Bishop Guido was present at the Lateran synod of Pope Calixtus II. On 8 March 1125, the new Pope, Honorius II, issued a decision on the long running dispute between the bishop of Siena and Bishop Guido of Arezzo. Ughelli I, p. 417. Kehr III, p. 152, no. 30; p. 153, nos. 35 and 36; p. 154, nos. 39 and 40. Schwartz, p. 203. Buianus (attested 1135, 1136)Boianus was deposed by Pope Innocent II pro et dolenda et horrenda destructione bonorum ecclesiasticorum seu episcopalium. Kehr III, p. 155, no. 41, note. Pasqui IV, p. 281. Maurus (attested 1136–1140)Maurus: Ughelli, pp. 417-418. Kehr III, p. 155, no. 41 Sede vacante (1142)Pope Innocent summoned to Rome the "graviores et honestiores" citizens of Arezzo, because the diocese had long been without a bishop: quia Aretina ecclesia pastore viduata pro electione novi episcopi aliquamdiu laboravit. Kehr, p. 155, no. 42.