Oreus

O: Maenad with wine-wreath	R: nymph Histiaea seated on stern of galley IΣTI / AIEΩN
silver tetrobol. This coin the most probably is Roman imitation of Histiaean issue struck in Macedonia during Roman military campaign circa 168 BC.

Oreus (Ancient Greek: Ὠρεός - Ōreos), known before the 5th century BC as Histiaea (Ancient Greek: Ἱστίαια - Histiaia), was an ancient town on the island of Euboea, Greece. It was situated near the north coast of the island, east of the present village Oreoi. It was situated on the river Callas, at the foot of the mountain Telethrium. It was an important city in classical antiquity due to its strategic location at the entrance of the North Euboean Gulf, in the middle of a large and fertile plain.

The name Histiaea is said to have derived after the mythical figure Histiaea, the daughter of Hyrieus. It was described by Homer in the Iliad as "rich in grapes". It was taken by the Persians in 480 BC, and after the Persians were expelled Histiaea became subject to Athens. In 446 BC, when the Euboean revolt against Athens was crushed by Pericles, the population of Histiaea was expelled and the town was populated with colonists from Athens. From that time, the town was referred to as Oreus. The expelled Histiaeans settled in Thessaly, and their new land was called Histiaeotis. Demosthenes describes the conquest of Oreus by Philip II of Macedon in his 341 BC Third Philippic. Pliny the Elder mentioned the town around 77 AD as abandoned, while Ptolemy (2nd century AD) mentioned the town as Soreos. Surface finds indicate that the site was still inhabited during the Roman, Byzantine and later times.

The present towns Oreoi and Istiaia in northern Euboea were named after this city.