Oreus ( - Oreos), known before the 5th century BC as Histiaea ( - 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.

Oreus ( - Oreos), known before the 5th century BC as Histiaea ( - 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.