Towers of Bologna

Each tower had a square cross-section with foundations between five and ten meters deep, reinforced by poles hammered into the ground and covered with pebble and lime.

Usually, some holes were left in the outer wall as well as bigger hollows in the selenite to support scaffoldings and to allow for later coverings and constructions, generally on the basis of wood.

The towers must actually have crowded Bologna in the Middle Ages and there has been considerable debate about their peak number before the first ones were demolished to avoid collapse or for other reasons.

He based his analysis mostly on the civic archives of real estate deeds, attempting to arrive at a reliable number of towers on the basis of documented ownership changes.

His approach resulted in the extraordinary number of 180 towers, an enormous amount considering the size and resources of medieval Bologna.

The most famous pair of towers are located at the intersection of the roads that lead to the five gates of the old ring wall (mura dei torresotti).

[1] As when one sees the tower called Garisenda from underneath its leaning side, and then a cloud passes over and it seems to lean the more, thus did Antaeus seem to my fixed gaze as I watched him bend... — Divine Comedy, Inferno, XXXI, 136-140[1] Never can my eyes make amends to me --short of going blind-- for their great fault, that they gazed at the Garisenda tower with its fine view, and --confound them!-- missed her, the worthiest of those who are talked about.