What is the famous leaning bell tower in Pisa, Italy?

The famous leaning bell tower in Pisa, Italy, is the Leaning Tower of Pisa. It is the freestanding campanile of Pisa Cathedral and stands in the Piazza del Duomo, alongside the cathedral, baptistery, and monumental cemetery.

Construction began in 1173, but the tower started sinking when work reached the second floor because it was built on weak, unstable subsoil over a shallow foundation. Long interruptions caused by wars gave the ground time to settle, allowing construction to continue. The tower was completed in stages, with the bell chamber added in 1372.

Its tilt is not an intentional design feature. Engineers later built some upper levels with one side taller than the other to compensate for the lean, giving the structure a slight curve. Stabilization work in the 1990s and early 2000s reduced the tilt from its dangerous pre-1990 measurement of about 5.5 degrees to roughly 3.97 degrees. The tower has seven bells and about 296 steps.