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.