Its exact site is not known. As reported in the 1913 Catholic Encyclopedia, W. M. Ramsay, said it was probably situated on the western side of the Lake of Nicaea (Isnik-Ghueul), near Bazar-Keui, between Kios (now Gemlik) and Nicaea (Isnik). The 2013 Annuario Pontificio places it at Pazarköy.
The first known bishop, Alexander, was consecrated by John Chrysostom about 400. Other bishops are
- Gerontius (451),
- Cyriacus (518),
- Sisinnius (680),
- Georgius (787),
- and Anthimus in 878.
At the Council of Chalcedon (451) the see had been the object of a sharp contest between the metropolitans of Nicomedia and Nicaea about jurisdiction. Basilinopolis was finally made by the council a suffragan of Nicomedia; and it remained so until about 1170 under Manuel Comnenus.
- Mansi, VII, 305.
- Hist. Geogr. of Asia Minor, 179.
- Annuario Pontificio 2013 (Libreria Editrice Vaticana 2013 ISBN 978-88-209-9070-1), p. 847
- Lequien, Oriens Christianus, I, 623-625.
- Mansi, ibid., 301-314.
- Hierocles, Synecdemos, ed. Parthey, 169.
- Annuario Pontificio 2013 (Libreria Editrice Vaticana, 2013, ISBN 978-88-209-9070-1), p. 46