Portara (Main Gate) and Byzantine Walls of Thessaloniki, Thessaloniki

The Walls of Thessaloniki once encircled the entire city, forming a continuous defensive ring from Late Antiquity through the Ottoman period. Large sections, especially along the seafront, were dismantled between the 1860s and 1874 during Ottoman-era redevelopment aimed at opening the city toward the sea.

The surviving walls date mainly to the late 4th century, when Thessaloniki’s fortifications were extensively rebuilt in the early Byzantine period, incorporating earlier Roman defenses from the late 3rd century. They follow a typical Late Roman construction technique, with alternating courses of stone and brick designed for strength and resilience.

Today, about 2.5 miles of the walls remain, roughly half of their original length. In places, they rise 33–39 feet high and reach widths of up to 15 feet. On the northeastern side, the walls climb the slopes of the Upper Town and connect with the Acropolis and the Heptapyrgion Fortress, forming the city’s most heavily fortified zone.

Throughout the Byzantine period, the walls were repeatedly repaired and reinforced, particularly in the 14th century. The fortification system included multiple gates and posterns, the most prominent surviving example being the Main Gate, recognizable today by its layered brickwork reflecting successive phases of repair. The circuit was also punctuated by numerous towers, several of which still survive.

The Walls of Thessaloniki are included in the UNESCO World Heritage List as part of the Paleochristian and Byzantine Monuments of Thessaloniki, recognizing their role in the city’s long and continuous defensive history.