Looking at this picture [1] of Bologna’s skyline from the sixties it seems it could be pretty realistic. The skyline has changed drastically and now you have many more tall buildings that make the remaining tower seems shorter. Also, I think the strangeness of the picture is due to the number of towers, but afaik there were around 100 towers in the city in the 13th century.

[1] https://it.m.wikipedia.org/wiki/Torri_di_Bologna#/media/File...

There are documents from the time and even paintings from later times, supporting these projections. You can see a partial list of the towers that have since disappeared here : https://www.torridibologna.it/torri-scomparse/ . There were probably more that we just don't have documents for.

Dante famously described Bologna as selva turrita, a forest of towers. It really was as crowded as that.

I don't know how tall are those in the first image, but consider that several towers reach beyond 300 feet (90 meters today), and documents point out that few reached beyond 330 in middle ages.

[edit]

This, existing, tower appear to approximate the height of those in that image:

https://static.bolognawelcome.com/immagini/bb/ec/bd/1b/20220...

Someone did look into exactly that. There is no supporting document regarding the actual height. And it does look like it is exaggerated for impact purposes. So they did have towers, they were clearly higher than the rest of the other buildings... Might have been this tall? Maybe. Or maybe not.