Greek peninsula in the Aegean Sea, itself having three peninsulas.
It is southeast of Thessalonica, and generally shared the same fate as that city. In the mid-14th century however the central and eastern districts of Chalcidice were in the vast Serbian Empire of Stephen Duãan, while the western district, together with Thessalonica, formed a Byzantine enclave.
In modern Greece the peninsula is a nome (department), except for the part of the eastern peninsula around Mount Athos, which is an autonomous religious community. The nome belonged to the region of Macedonia until 1987 and since then to the new region of Macedonia East & Thrace.