Bolu (Greek: Vithinion, Latin Bithynium or Claudiopolis) is a town in Turkey, and administrative center of the Bolu Province. Bolu is on the old highway from Istanbul to Ankara, which climbs over Mount Bolu, while the new motorway passes through Mount Bolu Tunnel below the town.
Bolu was part of one of the Hittite kingdoms around 2000 BC and later 500 BC became one of the leading cities of the Kingdom of Bithynia. Strabo (XII, 4, 7) mentions a Hellenistic town, Bithynium (Claudiopolis), celebrated for its pastures and cheese, which according to Pausanias (VIII, 9) was founded by Arcadians from Mantinea.
In the Ancient Roman era, as is shown by its coins, the town was commonly called Claudiopolis after Emperor Claudius. It was the birthplace of Antinous, the posthumously deified favourite of the Roman Emperor Hadrian, who was very generous to the city, and his name was later added to that of Claudius on the coins of the city. Emperor Theodosius II (408-50) made it the capital of a new province, formed out of Bithynia and Paphlagonia, and called by him Honorias in honour of the Emperor Honorius.