What I've learned about the symbol of region Macedonia's capital city is that in ancient times on the place of the White Tower there has been a Byzantine fortification. In the 15th century, when the city fell under Ottoman Rule, the construction has been used as a prison and also as a place for mass executions, which explains why its name was "The Red Tower" then.
More about this image here: https://sumfinity.com/hdr-photos/greece/thessaloniki/thessaloniki-white-...
