1, the Leaning Tower of Pisa tilted because of the soft foundation soil. The Leaning Tower of Pisa was started in 1174 AD, and completed in 1350, all made of marble. The tower began to build is upright, but built to the third floor, due to the foundation is not deep, the upper layer of low strength, the tower began to tilt subsidence, the project was suspended. 94 years later, and re-construction, and strengthened a series of anti-tilt measures. After more than 600 years of wind and rain, the tower stands tall, "oblique and downward tilt", making the tower famous.

2, the Leaning Tower of Pisa is the freestanding bell tower of the Cathedral of the Square of Miracles in the city of Pisa, Italy, which was built in August 1173 by the famous architect Nano Pisano. The Leaning Tower of Pisa is 58.36 meters high from the foundation to the top of the tower, and was first found tilted in 1174, its bold circular architectural design showed its originality to the world, and the United Nations Educational, Scientific and Cultural Organization's World Heritage Committee decided at its 11th meeting to include it in the World Heritage List.