The administrative center of the province, Giresun (pop. 56,000) lies on a small rocky peninsula which was once fortified. It is a port exporting wood and hazelnuts. Notable sights include the tombs of Seyyidi Vakkas and Osman Aga and an 18th century church. From the town a wide depression leads up to a flat-topped conical hill crowned by a
Byzantine fortress. Just outside the harbor is the little island of Giresun Adasi (ancient Aretia) where according to legend the Argonauts landed. The island was uninhabited and had a temple dedicated to the war god Ares. The ruins of a Byzantine monastery can be found there.
Giresun occupies the site of ancient Kerasous, founded by Miletus in the seventh century B.C. Xenophon and his Ten Thousand halted here on their march back to the sea. The place was later named Pharnakeia after King Pharnakes (grandfather of Mithradates the Great) who settled families from Kotyora (Ordu) in the town. During the war with the Romans, Mithradates moved his harem to Pharnakeia.
The present name of Giresun apparently owes its origins to the Roman general Lucullus who found a particularly good type of cherry here (Greek = "kerássi", Latin = "cerasus" and Turkish = "kiraz") which he later took back to Rome.