The walls were re-erected with more elaborate fortification in 390 AD, during the reign of Byzantine emperor Theodosius, who was also the last ruler to be crowned as the monarch of both halves of the Roman Empire. Back then, their purpose was to protect the city of Thessaloniki from attacks of hostile parties and withstand external threats, keep the city thriving in times of war, siege or raid. These Byzantine Walls of Thessaloniki held against the siege of the Ottoman army for eight long years, from 1422 to 1430, which proves the strength and resilience that the walls had.

Later in the 19th century, the Ottomans brought down many parts of the walls to extend the city’s urban stretch and remap the city. They made a lot of changes, especially on the sea-facing side, and also added some important towers and fortifications. One can find different carvings in ancient scripts on the walls, as well as pictures and symbols like stars and crosses. Presumably, both Roman and Ottoman cultures have left their marks on the great walls they created.

The Tower of Trigoniou near the Acropolis of Thessaloniki is an important one. Built in the late 15th century, this tower was once used as an armoury and artillery, and also a lookout post. Now, it is frequently visited by tourists to witness first-hand the grandeur of the architecture and also for a magnificent view of the Gulf of Thermaikos.

Yedikule, or the Fortress of the Seven Towers near the north-east of the Acropolis, is also a continuation of the walls. It served as a redoubt for the Ottomans and later on as a seat for garrison and prison as well.

The grandeur and intimidation that the walls still reflect is only a glimpse of how they served as the first line of defence for the city for over centuries, standing sentinel all day and night. More can be learnt about the history and significance of the walls from the Museum of Byzantine Culture in Thessaloniki.