Synnada was situated in the south-eastern part of eastern Phrygia, or Parorea, thus named because it extended to the foot of the mountains of Pisidia, at the extremity of a plain about 60 stadia in length, and covered with opium plantations.
Synnada is said to have been founded by Acamas who went to Phrygia after the Trojan war and took some Macedonian colonists. It enters written history when the Roman consul Gnaeus Manlius Vulso passed through that city on his expeditions against the Galatians (189 BCE). After having belonged to the kingdom of the Attalids, it became the capital of a district of the province of Asia, except on two occasions during the last century of the Roman Republic when it was temporarily attached to Cilicia. Under Diocletian at the time of the creation of Phrygia Pacatiana, Synnada, at the intersection of two great roads, became the metropolis (capital). In Strabo's time it was still a small town, but when Pliny wrote it was an important place, being the conventus juridicus for the whole of the surrounding country. Cicero mentions that he passed through Synnada on his way from Ephesus to Cilicia. The city was celebrated throughout the Roman Empire on account of the trade in a beautiful kind of marble, which came from nearby quarries and was commonly called Synnadic marble, though it came properly from a place in the neighborhood, Docimia, whence it was more correctly called Docimites lapis. This marble was of a light color, interspersed with purple spots and veins. On its coins, which disappear after the reign of Gallienus, its inhabitants call themselves Dorians and Ionians. Under Ottoman rule it became the city of Schifout Kassaba in the vilayet of Broussa.
Christianity was introduced at an early date into Synnada. The Martyrologium Hieronymianum mentions the martyrs Trophimus and Dorymedon. A reliquary of Tromphimus in the form of a sarcophagus with his bones was discovered here and transported to the Bursa museum; it may date to the 3rd century. Eusebius of Caesarea speaks of its pious bishop Atticus who entrusted to the layman Theodore the duty of instructing the Christians.
For a list of other bishops see Le Quien, Oriens christianus, I, 827. Mention must be made of:
- Procopius (321); Cyriacus, friend of St. John Chrysostom
- Theodosius and his competitor Agapetus, at first a Macedonian heretic
- Severus (431) Attended Council of Ephesus
- Marinianus (448-51)
- Theogenes (536)
- Severus (553)
- St. Pausicacus, during the reign of Emperor Maurice, honoured by the Greek Church on 13 May
- Cosmas, 680
- John, adversary of the iconoclasts in the time of Patriarch St. Germanus
- St. Michael, honoured by the Latin and Greek churches 23 May, died 23 May, 826, in exile for his zeal in defending the worship of images
- Peter under Patriarch Photius
- John under Photius
- Pantaleon under Leo the Wise
- Leo under Basil II
- Nicetas in 1082
- Georgios at the Council of St. Sophia, about 1450, if one can believe the apocryphal Acts of this council, which perhaps never occurred.
The last Bishop of Synnada spoken of in the documents, without mentioning his name, probably lived under John Cantacuzenus (see "Cantacuz. Hist.", III, 73) and probably never lived at Synnada on account of the Turkish conquest.
In 1385 the see was committed for the Greek Church to the Metropolitan of Philadelphia. The metropolitan see of Synnada continues to be included in the list of titular sees recognized by the Roman Catholic Church. In 1963 it was assigned to Marcel-François Lefebvre, who later became a traditionalist Catholic dissident. Since the Second Vatican Council no new appointments have been made to this eastern titular see.
- Pedro Rafael González y Calixto † (15 Jun 1893 Appointed – 14 Jul 1893 Succeeded, Archbishop of Quito)
- Henri-Victor Altmayer, O.P. † (28 Aug 1902 Appointed – 12 Nov 1930 Died)
- José Belisario Santistevan Seoane † (22 Nov 1930 Appointed – 30 Mar 1931 Died)
- Giacomo Ghio † (20 Oct 1931 Appointed – 4 Nov 1935 Died)
- Ildebrando Antoniutti † (19 May 1936 Appointed – 24 May 1962 Appointed, Cardinal-Priest of San Sebastiano alle Catacombe)
- Marcel-François Lefebvre, C.S.Sp. † (7 Aug 1962 Appointed – 10 Dec 1970 Resigned) 
- Richard Talbert, Barrington Atlas of the Greek and Roman World, (ISBN 0-691-03169-X), Map 62 & notes.
- Livy xxxviii. 15, xlv. 34.
- Strab. xii.
- Plin. H.N., v. 29
- Cic. ad Att. v. 20; comp. ad Fam. iii. 8. xv. 4
- Strab. l. c.; Plin. xxxv. 1; Stat. Silv. i. 5. 36; Comp. Stephanus of Byzantium s. v.; Ptolemy v. 2. § 24; Martial, ix. 76; Symmach. ii. 246.
- Acta Sanctorum, VI September, 9 sq.
- Mendel, "Bulletin de Correspondance Hellénique", XXXIII (1909), 342 sq.
- Church History, VI, 19.
- Eusebius, Church History, VII, 7.
- Synnada in Phrygia at catholic-hierarchy.org
- This article incorporates text from a publication now in the public domain: Smith, William, ed. (1854–1857). "Synnada". Dictionary of Greek and Roman Geography. London: John Murray.
- This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913). "Synnada". Catholic Encyclopedia. New York: Robert Appleton Company. "Synnada"
- Louis Robert, Lettres d'un évêque de Synnada (Paris, 1962).