How far has the Leaning Tower of Pisa leaned?

The Leaning Tower of Pisa has leaned approximately 4 degrees from vertical, which translates to about 15 feet (4.5 meters) from the vertical axis at its highest point. The tower's tilt began during its construction in the 12th century due to unstable foundation soil. After extensive restoration efforts in the late 20th and early 21st centuries, the tilt has been stabilized, preventing further leaning.