The leaning tower of Pisa, in Italy, it is famous because of its tilt. Above the entrance there is an inscription which says that the contraction began in 1173. it was built as a bell Tower to let people know if there was an emergency and for the catholic people to wake up for church.
They stopped at the third floor because the tower began to tilt. The subsoil and the foundations weren't strong enough to keep the tower standing straight. To compensate for the tilt they constructed 1 side taller than the other.
In the tower of PIsa there is a spiral staircase with 300 well worn stone steps. Each floor has pillars and arches. From the top there are panoramic views of Pisa.