Architecture in Thessaloniki spans centuries and empires, but it is easy to pinpoint the zenith of architectural achievement in the city. During the early Middle Ages, when Constantinople was the center of power in Europe, Thessaloniki served as an unofficial second capital of the Byzantine Empire. It was during this period that Thessaloniki experienced an unprecedented flowering of the arts and architecture.

The soaring Hagia Sophia church , though it is less famous than the Constantinople church of the same name (today a museum), exemplifies the artistic skill of the Byzantine Empire, with its astonishingly detailed mosaics and intricate gild work. Another important work of architecture dating from the Byzantine era is the great White Tower , commissioned in the 1500s by Suleyman the Magnificent. Appropriately, the White Tower currently holds a museum of Byzantine culture where it is possible to learn even more about Byzantine architecture.

Earlier examples of architecture in Thessaloniki abound, although they are mostly in ruins. The Roman Arch of Galerius has suffered damage from earthquakes, but a large portion of it still stands as a testament to Roman skill in monument building. Most of the architecture from ancient Greece is gone, but you can visit Thessaloniki's Hippodrome square , once the site of a Greek chariot-racing stadium with the same name.