The Leaning Tower of Pisa is the campanile, or freestanding bell tower, of the cathedral of the Italian city of Pisa. Although intended to stand vertically, the tower began leaning to the southeast soon after the onset of construction in 1173 due to a poorly laid foundation and loose substrate that has allowed the foundation to shift direction.
The tower was built in three stages over a period of about 177 years. In May 2008, after the removal of 70 tons of earth, engineers announced that the Tower had been stabilized so that it had stopped moving for the first time in its history. They declared it would be stable for at least 200 years. It leans to the southwest.