Thessaloniki, also known as Thessalonica, Saloniki or Salonica, is the second-largest city in Greece, with over 1 million inhabitants in its metropolitan area, and the capital of the geographic region of Macedonia, the administrative region of Central Macedonia and the Decentralized Administration of Macedonia and Thrace. It is also known in Greek as η Συμπρωτεύουσα, literally "the co-capital", a reference to its historical status as the Συμβασιλεύουσα or "co-reigning" city of the Byzantine Empire alongside Constantinople.
Thessaloniki is located on the Thermaic Gulf, at the northwest corner of the Aegean Sea. It is bounded on the west by the delta of the Axios. The municipality of Thessaloniki, the historical center, had a population of 325,182 in 2011, while the Thessaloniki Urban Area had a population of 824,676 and the Thessaloniki metropolitan area had 1,030,338 inhabitants in 2011. It is Greece’s second major economic, industrial, commercial and political centre; it is a major transportation hub for Greece and southeastern Europe, notably through the Port of Thessaloniki.