When leaning becomes falling

"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."

https://www.nytimes.com/2023/10/30/world/europe/italy-leaning-garisenda-tower-bologna.html