The city's Byzantine walls and castles are among past remnants keeping previous eras alive and even today command a sense of prestige and power.
The perimeter of Thessaloniki's walls is almost 5 km long and they range in height from 9-11 meters. If you look close you will see that they are decorated with crosses and ancient Greek symbols. Similar symbols can be seen on the walls in Istanbul.
The Acropolis has stood on the highest spot in the city since ancient times, when it functioned as a defense in the event of invasion. Probably during the times of the Palaiologoi Dynasty (14th century) a third tier fortification was built on the northeastern side of the Acropolis and the entire city, in order to be the last and strongest defense had strong walls and seven towers, and was called Eptapyrgio.
Here, you will also see the Tower of Yedi Kule, the middle one of the 7 towers which was built shortly after the fall of Thessaloniki by Cavus Bey(1430).