Salonica or Thessaloníki, city and port in north-eastern Greece, one of the largest cities in Greece, and the chief port and commercial centre of Central Macedonia. The city is the capital of Salonica department, at the northern end of the Thermaic Gulf. Key industries in the city include iron foundries, shipyards, and textile and flour mills; major exports are mineral ores and tobacco. The city is also the seat of the Aristotle University of Salonica (1925).

In the 1st century ad, the apostle Paul preached to the Thessalonians in Salonica, then in the Roman province of Macedonia. The city was occupied in the 10th century by the Saracens and in the 12th century by the Normans. In the 13th century Salonica became part of the Byzantine Empire; many fine examples of Byzantine art survive in the city, particularly the mosaics in some of its historic churches, including the basilica of Hagia Sophia and the church of St George. Salonica was under Turkish occupation from 1430 to 1912, when it surrendered to a Greek army. George I of Greece was assassinated here in 1913. The city was occupied by the Germans in World War II. Early Christian and Byzantine monuments of Salonica were inscribed on the UNESCO World Heritage list in 1988. Population 363,987 (2001).