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 di

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/ 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.