Olynthus is an ancient city in present-day Chalcidice, Greece. It was built mostly on two flat-topped hills 30–40m in height, in a fertile plain at the head of the Gulf of Torone, near the neck of the peninsula of Pallene, about 2.5 kilometers from the sea, and about 60 stadia from Poteidaea.

Chalkidiki, also known as Chalcidice, is a peninsula and regional unit of Greece, part of the region of Central Macedonia, in the geographic region of Macedonia in Northern Greece. The autonomous Mount Athos region constitutes the easternmost part of the peninsula, but not of the regional unit.