(Coordinates: ). Germanicopolis (Greek: Γερμανικόπολις) also known as Caesarea in Bythinia (not to be confused with Caesarea Germanica which was a different town altogether), was an ancient town in Bithynia, on the Gelbes river, not far from Prusa (modern Bursa in Turkey). In earlier times it was called Helge, Helgas or Booscoete (Βοὸς κοίτη), Plin. v. 40. Modern scholars locate the town at the village of Tahtalı
In Byzantine times the town was the site of a Bishopric and the names of a number of bishops of the town have came down to us, Paulus and John, attendees of the Synods of Constantinople, and four bishops named by Le Quien; Theodosius, Theodorus, Constans and Theopistus.