A Leaning Tower in Italy (Not Pisa) Becomes a Worry

The Garisenda Tower in Bologna is not as famous as the Tower of Pisa, but it leans a little more. Lately, though, the dynamic of its movement has become worrisome, and city officials decided recently that the central square where it stands a few meters apart from the much taller Asinelli Tower will be closed off, most likely for years.

The tower, which, along with the Asinelli Tower, makes up the “two towers,” a symbol of the city, has historically slanted four degrees. But recent surveys have found traces of unexpected rotation in its incline and other imperceptible movements that need to be studied more carefully, the authorities said.

“The point is not that the tower is collapsing,” Mayor Matteo Lepore of Bologna said in a phone interview. “We have been monitoring it since 2018 like a patient in a hospital, and we know now that it needs to be secured and restored, and decided to start immediately.”

He explained that the area was closed off last week to allow a more thorough monitoring of the site, possible only without traffic noise and interference.

For years, a committee of national experts has been studying the data collected from the Garisenda Tower, thanks to acoustic sensors, optical fibers, a GPS on its top, a pendulum and systems to monitor the water table that runs underground, close to the tower. In 2021, the base of the tower was completely encircled with large iron rings to prevent any cracks in its fragile selenite stone. Since the late 1990s, other iron rings have been used to reinforce the upper portion of the tower, made of typically Bolognese red bricks.

The ground and the tower’s foundations started sinking after construction in the early 1100s, probably because of a construction error, and in the middle of the 1300s, the tower was shortened over fears that it could collapse. Its “leaning forward” scared even Dante Alighieri, who in “Inferno,” the first volume of his “Divine Comedy,” compared it with the appearance of a giant, Antaeus.