Prusias on the Hypius

formerly Cierus, Kieros (Üsküb)

A city of Bithynia (northwestern Asia Minor), situated on a defensible hill at the foot of Mount Hypius overlooking the small plain of a river, likewise called Hypius (Düzce). Originally known as Cierus, and colonized from central Greece (as the local designations of surviving tribal divisions, Megaris and Thebais, bear witness), the place was bought from the Bithynian monarchy by Heraclea Pontica (Ereǧli) but recaptured by King Prusias I (c 230–182) and given his name.

It was an important station on the road from Nicomedia (İzmit) in Bithynia to Amastris (Amasra) in Paphlagonia. Coinage of Roman imperial times, which seems to have started under Vespasian (AD 69–79) and continued until Gallienus (253–68), depicted a figure engaging in sacrifice, identified as Caracalla (211–17), who visited the city (like Elagabalus [218–22] after him). By the early fourth century it was the seat of a bishopric.

The surviving remains of Prusias include a colonnaded street, fortifications embodying a gate, a theater of the second century AD, and a three-arched bridge which remained intact until recent inundations. Floor mosaics depicting mythical scenes have been found outside the walls. (The city has to be distinguished from Prusias on the Sea [formerly Cius, now Gemlik] and Prusa [Bursa, Brusa], which were likewise in Bithynia).