Thessaloniki, a Greek port city situated on the Thermaic Gulf of the Aegean Sea, is rich in historical remnants from its Roman, Byzantine, and Ottoman past, particularly in the area of Ano Poli, the upper town. The remains of the 4th-century palace of Roman Emperor Galerius, including the Rotunda which has served as both a church and a mosque, are notable landmarks. The city center, which was largely devastated by the Great Fire of 1917, has been reconstructed with a contemporary European design.