The Due Torri are what Bologna looks like in your memory after you leave. The taller Asinelli (97 metres) and the dramatically leaning Garisenda (48 metres) stand at the meeting point of the city's medieval main streets, where the road from Florence met the road from Padua. Both were built by noble families in the early twelfth century as defensive towers and demonstrations of wealth.
Note: as of late 2023 the Garisenda has been judged structurally unstable and the surrounding area is fenced off; tower climbing has been suspended for an extended consolidation project. Check current status before visiting if climbing the Asinelli is on your list. From below they still anchor the heart of the old city.