A titular see of Asia Minor.
The city was founded 676 B. C. by the Megarians on the Bithynian coast, opposite the place where a little later Byzantium rose.
It was captured by the Persian general Otanes after the expedition of Darius against the Scythians. Allied alternately with Athens and Sparta, it became eventually a part of Bithynia, and in 74 B. C. passed over to the Romans, who lost it temporarily to Mithradates.
In the imperial period it was a free city, but was dismantled by Valens (364-78). The Persians held it from 616 to 626.
Chalcedon was the birthplace of the philosopher Xenocrates, a disciple of Plato, and of the sculptor Beotes. The virgin St. Euphemia and her companions suffered martyrdom there, probably under Galerius (305-11). It is in her magnificent church that the Fourth General Council against Eutyches, known as the Council of Chalcedon (451), was held.
This church was situated on the top of the hill at Haïdar-Pasha (Haider Pasha); it was destroyed by Suleiman to build his mosque in Constantinople. Among other martyrs who suffered at Chalcedon mention may be made of the Persian St. Sabel and his companions. Chalcedon was an episcopal see at an early date; after the great council it became a metropolis, but without suffragans. There is a list of its bishops in Lequien (I, 599), completed by Anthimus Alexoudes in "Anatolikos Aster" (XXX, 108), revised for the early period by Pargoire in "Echos d'Orient" (III, 85, 204; IV, 21, 104).
Among others are St. Adrian, a martyr; St. John, Sts. Cosmas and Nicetas, during the Iconoclastic period; Maris, the Arian; Heraclianus, who wrote against the Manichæans and the Monophysites; Leo, persecuted by Alexius Comnenus.
The titular Latin see is suffragan of Nicomedia. Lequien (III, 1019) mentions eight Latin bishops, from 1345 to 1443; Eubel (I, 199; II, 141) has ten names, from 1293 to 1525. Five other titular bishops of the sixteenth century are mentioned in the "Revue bénédictine" (1904, 144-45, 155-56).
Chalcedon is to-day Kadi-Keui (Kadikoi). It has about 30,000 inhabitants: 15,000 Greeks, 5000 Armenians (500 Catholics), 2000 Latins, 6000 Mussulmans, 2000 Jews, 200 Protestants.
The Latin parish is conducted by the Assumptionists; they have also a seminary for Catholic Greeks, with a Greek chapel, and a high school for Oriental studies, which publishes a review, the "Echos d'Orient". The Christian Brothers have there a large college with commercial and elementary courses. The Dames de Sion have a school for girls; the Sisters of the Immaculate Conception of Lourdes a convent; the Capuchins a scholasticate. There are also public chapels belonging to the Franciscans and the Catholic Armenians.
The Armenian Sisters of the Immaculate Conception have a house at Chalcedon, and the Armenian Mechitarists a college. Two Greek churches, one Armenian, and one English Protestant church complete the list of Christian institutions.
At Haïdar-Pasha, the port of Kadi-Keui and head station of the Anatolian railway to Bagdad, the Assumptionists have a public chapel, and there are schools conducted by the Christian Brothers, and the Oblate Sisters of the Assumption, also a synagogue, German Protestant and Jewish schools, and an English cemetery, with a monument to the soldiers who died in the Crimean War.
At Famaraki (ancient Hiereia) the Assumptionists have a chapel, and the Oblate Sisters of the Assumption a school. Near Kadi-Keui and within the limits of the Greek diocese are places of interest.
Scutari is the Turkish name of Chrysopolis, a city which the Mussulmans consider sacred on account of its cemetery and its beautiful mosques. It has a hospital for lepers and a Catholic church, cared for by Georgian Benedictines, also schools in charge of the Marists and of Sisters of Charity. It was there that Licinius was defeated by Constantine (324); there also lived St. Maximus, the Confessor (580-662), the hero of the Monothelite controversies.
Tchiboukli, on the Bosphorus, is the Byzantine Irenaion, where stood the famous monastery of the Acœmetæ, founded by St. Marcellus; at Kalamish (the port of Eutropius) lived the stylite, St. Luke; Djadi-Bostan is the ancient Rufiniana, where the famous councils Ad Quercum were held in 397 and 403. In the vicinity were the monasteries of St. Hypatius and St. John. On the Kaish-Dagh lived St. Auxentius, St. Bendidianus, and St. Stephen, and at Touzla (Cape Acritas) St. Athanasius of Paulopetrion and St. Gregory.
Finally, in full view of Kadi-Keui, are the celebrated Prince's Islands, with their numberless political and ecclesiastical associations.