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.

Macedonia is a geographic and former administrative region of Greece, in the southern Balkans. Macedonia is the largest and second-most-populous geographic region in Greece, with a population of 2.36 million. It is highly mountainous, with major urban centres such as Thessaloniki and Kavala being concentrated on its southern coastline. Together with Thrace, along with Thessaly and Epirus occasionally, it is part of Northern Greece. Greek Macedonia encompasses entirely the southern part of the wider region of Macedonia, making up 51% of the total area of that region. Additionally, it widely constitutes Greece's borders with three countries: Albania to the northwest, North Macedonia to the north, and Bulgaria to the northeast.