The Leaning Tower of Pisa is one of the most remarkable architectural structures in the world. Here are 10 interesting facts about its history and construction:

​Purpose: The tower was built as a freestanding bell tower (campanile) for the Cathedral of the Italian city of Pisa.

​Construction Time: It took nearly 200 years to complete, with work beginning in 1173 and finishing in 1372.

​The Cause of the Lean: The tower began to tilt during construction because it was built on soft ground made of clay, fine sand, and shells, which could not support the structure's weight.

​Height: It stands approximately 56 meters (about 183 feet) tall on its highest side.

​Weight: The entire structure weighs an estimated 14,500 metric tons.

​The Design: It is built in the Romanesque style and features eight stories, including the bell chamber at the very top.

​Correction Attempts: Throughout history, engineers tried to correct the lean by building the upper floors with one side taller than the other, which actually makes the tower slightly curved.

​Stabilization: Between 1990 and 2001, the tower underwent massive restoration work to stabilize it, reducing the tilt by about 44 centimeters to ensure it doesn't fall.

​Bells: There are seven bells in the bell chamber, each representing a different note of the musical scale.

​World Heritage: It was designated a UNESCO World Heritage Site in 1987 as part of the Piazza del Duomo complex.