Then again part of being a true citizen of Bologna is to have incorrect information on some of the landmarks there.
They were pretty common in every big enough city in Italy at that time.
Another good example would be Perugia. At a certain point it was even called “turrita”, literally “of towers”. As of now there’s only one left, Sciri Tower[0].
[0]: https://en.wikipedia.org/wiki/Torre_degli_Sciri?wprov=sfti1#...
The article is actually quite disappointing as it’s really just clickbait content for a video that I have no interest in watching.
Its not like they rented out office space like in downtown Manhattan. Also no factories that required thousands of workers. So I'm not sure the modern analogy of square footage applies.
They fell out of favor by the 16th century. Coincidentally about the same time as cannon starting being very effective.