English: Interior of the Church of Saint Demetrius (Hagios Dimitrios) which honors the patron saint of Thessaloniki.

Demetrius was born in 280 CE, the son of a wealthy Roman military commander of Thessaloniki. He secretly became a Christian when he was young. He followed in his father’s footsteps becoming an army officer, but when the Roman emperor ordered the killing of Christians, Demetrius refused and revealed his faith. He himself became a victim of the Christian purge when he was run through with spears while imprisoned at the baths on this site around 306 CE.

After Christianity was legalized in 311 CE, a small chapel was built over the ruins of the Roman baths which attracted pilgrims. In 413 CE a grand basilica was constructed here by the subprefect Leontius who believed St. Demetrius had cured him of a serious illness. A fire in 634 CE necessitated rebuilding, resulting in the even larger basilica that stands today. The church was converted to a mosque in 1493 CE during the Turkish occupation and then back to a church again in 1912 CE when the city was liberated. The Great Thessaloniki Fire of 1917 destroyed the roof and upper walls of the church leading to decades of restoration, not reopening again until 1949 CE.

Thessaloniki (sounds like “thess aloe knee key”) is the capital of Greek Macedonia and the second-largest city in Greece after Athens. The city was named after Princess Thessalonike of Macedon, daughter of King Phillip II (reigned 359 BCE until his assassination in 336 BCE) and half-sister of Alexander the Great (King Alexander III, reigned 336-323 BCE). In 315 BCE she married Cassander, the ambitious de facto ruler of much of Greece starting in 317 BCE, who honored her by renaming the city of Therma. After various nefarious deeds, Cassander ultimately proclaimed himself the Macedonian king (reigned 305-297 BCE) with Thessalonike his queen.

The Romans conquered Macedon in 168 BCE.

The New Testament of the Bible contains two epistles the apostle Paul wrote to the Thessalonians. He visited Thessaloniki (Acts 17:1-14) in the middle of the 1st century CE when he left Asia Minor (modern Turkey) and came to southern Europe, both part of the Roman Empire, to promote Christianity.

Although Christianity was technically illegal in the Roman Empire, it was the people (religious traditionalists) not the government who persecuted Christians during the first two centuries CE. In the 3rd century CE government activism ebbed and flowed, culminating in the most severe Roman persecution of Christians, especially in the eastern provinces, following a series of edicts in 303 CE. In 311 CE the Edict of Tolerance by Galerius legalized Christianity in the eastern Roman Empire with the west added two years later. Christianity was decreed to be the official state religion in 380 CE.

The Roman Empire began experimenting with separate eastern and western administrative regions in 286 CE, ultimately dividing into two distinct entities in 395 CE. The eastern half has become known [starting with German historian Hieronymus Wolf in 1557 CE] as the Byzantine Empire (so-called because its capital was originally called Byzantium before being renamed Constantinople, today’s Istanbul). Thessaloniki became Byzantium’s second city after Constantinople.

In 1430 CE the city was taken over by the Ottoman Turks who promoted Islam while persecuting Christians. Large parts of the wall around Thessaloniki, including the entire seaward section, were demolished for a restructuring of the city. The Turks were ousted in 1912 CE. The Nazis occupied Greece during World War II, deporting and killing most of what had been a large Sephardic Jewish population in Macedonia.

The Paleochristian and Byzantine Monuments of Thessalonika were designated UNESCO World Heritage sites in 1988.

On Google Earth:

Church of Agios Dimitrios 40°38'20.13"N, 22°56'51.17"E