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.
Lake Abant is one of the amazing beauties that the city of Bolu provides. It is 34 kilometers (21 miles) southwest of the province, situated at an altitude of 1500 meters. The lake is a magnificent one with water lilies spread over, and the deep green forest surrounding it. There are high-quality accommodation establishments around the lake which deserves spending some time. It is frozen during the winter where people ice-skate on it.

Another wonder of Bolu is the Yedigoller (Seven Lakes) National Park which has an appeal beyond words. It’s about 42 km (26 mi) north from the center. Golcuk, an artificial lake 14 km (9 mi) south of the city, surrounded with green forests, is another lovely site for picnicking or trekking.

Kartalkaya on the Koroglu Mountains is a perfect resort for those who like skiing. It is one of the three best winter sports centers in Turkey. You will find quietness and sportive enthusiasm in Kartalkaya, at about 38 km (23 mi) southeast of the city. Aladag meadows are the other attractive tourist sites on these mountains.