Construction on the Leaning Tower of Pisa began in 1173 and finished in 1360. The tower's engineers began to notice the structure's tilt after they completed three of the planned eight stories.Continue Reading
At that point in the construction of the tower, war broke out in Italy for nearly a century, allowing the foundations to settle, likely creating stability that permitted the tower to lean at a precarious angle without collapsing completely. After restarting construction, engineers tried to compensate for the lean by making the floors taller on the leaning side. This approach, however, merely weighed the tower down more, exacerbating the sinking.
In the 20th and 21st centuries, engineers used modern materials to strengthen the tower and reduce the likelihood of collapse. Engineers also doctored the foundation to reduce the lean and stop it from leaning even further.Learn more about Middle Ages