Which famous tower leans to one side?

The Leaning Tower of Pisa is the famous tower that leans to one side.

Located in Pisa, Italy, the tower is the freestanding bell tower, or campanile, of Pisa Cathedral. Construction began in 1173, and the tower started leaning while only a few levels had been completed. Its foundation was too shallow for the soft, unstable ground beneath it, causing one side to sink more than the other.

Construction took place in stages over nearly two centuries, with the bell chamber completed in 1372. Builders tried to compensate for the tilt by making upper floors slightly taller on one side, which left the structure subtly curved as well as leaning. The tower’s famous tilt once reached about 5.5 degrees.

Engineering work between 1993 and 2001 reduced the tilt to roughly 3.97 degrees and stabilized the monument. The tower is about 56 meters tall and contains seven bells. It is part of the Piazza del Duomo UNESCO World Heritage Site, recognized in 1987. The Eiffel Tower and Empire State Building are famous landmarks, but neither is known for this historic lean.