The two towers are the symbol of Bologna and the expression of a type of construction that has characterized the city for centuries: Bologna, in fact, counted one hundred towers in the past. The towers were built by the wealthiest families to show their power and many of them also functioned as housing structures, called "tower-houses". Today twenty-two remain and the most famous of them are the Asinelli Tower and the Garisenda Tower. The Asinelli Tower is the highest hanging tower in Italy and measures 97.2 metres, with an inclination of 2.3 metres. Probably its construction was wanted by the Duke of Milan Visconti to keep an eye on the revolts of the Middle Market located in via Rizzoli, later the Municipality used it as a prison. The smaller tower, the Garisenda, is 48 meters high and has a projection of 3.2 meters. Dante Alighieri mentions it several times in his works "The Divine Comedy" and "The Rhymes".