Of the more than 100 noble towers that once gave medieval Bologna a skyline like San Gimignano's, 22 still stand — sometimes truncated, sometimes leaning, often embedded inside later buildings so that you don't notice them until you look up. The two main towers near Piazza di Porta Ravegnana (the Asinelli and Garisenda) get most of the attention, but there are clusters of others worth seeking out.
The Torre Prendiparte (Piazza Sant'Alessandro), at 60 metres, is the second tallest and has been converted into a single-suite hotel. The Torre Azzoguidi and Torre Galluzzi each lean perceptibly. A short walk in the old centre with a map of tower locations turns into a quiet treasure hunt and the best way to read the medieval social geography of the city.