These mini castles were built all over the city.
The reasons for the construction of so many towers are not clear. One hypothesis is that the richest families used them for offensive/defensive purposes during the period of the Investiture Controversy.
Only a few survive to the current day.
https://en.m.wikipedia.org/wiki/Towers_of_Bologna https://www.sciencedirect.com/science/article/pii/S1296207418306952
One hypothesis, the city built the towers in hopes of one day being the locale for an Assassin’s Creed game, thus improving tourism.
This reminds me of the Georgian Svan towers. These towers were also used as defensive fortification for families.
Bologna is also home to the oldest surviving university in the world
Towers were a part of the meta in Age of Empires II: Age of Kings…
Then they got nerfed in the Definitive Edition, so tower rushing became less popular as you can see.
