1. Weak Foundation: The tower was built on soft, unstable soil consisting of clay, sand, and silt. This weak foundation could not adequately support the weight of the tower, causing it to sink unevenly.
2. Design Flaw: The original design of the tower was flawed, as the foundation was not wide enough to distribute the weight of the structure properly. Additionally, the tower was built without any buttresses or structural support to counteract the forces that would cause it to lean.
3. Construction Delays: The tower's construction was interrupted for nearly a century due to wars and financial difficulties. During this time, the tower had already started to lean, but it was allowed to continue leaning without any corrective measures being taken.
4. Soft Subsoil: The subsoil of Pisa is a mixture of clay, sand, and water, which is not strong enough to support the weight of the tower evenly. The water content in the soil also made it more susceptible to shifting and settling.
5. Weight Distribution: The weight of the tower is not evenly distributed throughout its structure. The upper floors of the tower are heavier than the lower floors, creating an imbalance that contributes to the leaning.
6. Tourist Attraction: The Leaning Tower of Pisa is a popular tourist attraction that sees millions of visitors each year. The constant foot traffic and vibrations caused by tourists climbing the tower have also contributed to its leaning.
Efforts have been made to stabilize the tower and prevent further leaning. In the late 20th century, an extensive restoration project was undertaken to reinforce the foundation and prevent the tower from collapsing. The tower is now open to visitors, but the number of people allowed inside is limited to prevent excessive strain on the structure.
