Bologna is filled with lots of narrow side streets and so many of those little streets have some sort of surprise along them. Beautiful colors, incredibly old palaces, and quite often a tower. The city, during the 12th and 13th centuries was like a medieval New York City, with skyscraping towers everywhere. There were possibly as many at 180, though most likely not more than 100 at any one point.
Most are gone now, though Le Due Torri (Asinelli and Garisenda) are now symbols of the city. However, there are still a fair few Bologna towers left. As you glance down a side street, you may find one of these many towers rising up unexpectedly. Just another reason to love this beautiful city.
For what it’s worth, I believe this is the Torre Prendiparte, which is around 900 years old. It was a former prison and defense tower, but it seems it has been renovated and turned into a B&B and event spot. You can also ascend to the top, for what is surely a spectacular view.