The Leaning Tower of Pisa has never really been straight

Soon after building started in 1173, the foundation of the Pisa tower settled unevenly. Construction was stopped, and was continued only a 100 year later. It then became visibly clear that the Tower of Pisa is leaning, tilting to the south.
Since regular measuring of the tower began in 1911, the top of the tower has moved 1,2 millimetres (0,05 inch) per year. Today the top of the Tower of Pisa is some 5,3m (17,4 ft) off-centre.
After the bell tower of the Cathedral of Pavia collapsed in 1989, the Consorzio Progetto Torre di Pisa (Tower of Pisa Project Consortium) commissioned engineers to stabilise the Leaning Tower. Because the Tower tilted in different directions in its first years, it is slightly curved, like a banana. Engineers are working on the footing of the Tower rather than the structure, hoping to ease the top back about 20 cm (about 8 inches). But it means that the 800-year old tower will remain leaning.