Leaning Tower of Pisa

The enclosing walls at the base of the tower are 4.09 m long, while the top is 2.48 m long. The staircase inside the bell tower has 251 steps.

An excerpt from the article 20 facts about Leaning Tower of Pisa
The campanile reaches a height of 56,705 m and its deviation from the vertical increases by one millimeter per year.