Begun in 1173, probably under the direction of Bonanno Pisano, the Bell Tower soon ran into problems around the subsidence of its foundations, indeed to the point of suspending worksite activity at length, which only resumed at the end of the following century under the direction of Giovanni di Simone. Of great interest are the seven bronze bells cast between the 15th and 18th century, the sound of which reproduce the notes on the musical scale.

The Tower of Pisa is often associated with the first experiments on the motion of weights, which Galileo Galilei is said to have conducted between 1590 and 1591 in the presence of students and teachers of the University of Pisa. The historical truthfulness of the fact, however, appears somewhat dubious, even though a Latin inscription at the entrance of the tower recalls that, from the peak of the Bell Tower, Galileo conducted his famous experiments on falling bodies. «And so, - writes his student Vincenzo Viviani in the Racconto istorico della vita di Galileo (1654) - with the great disconcertment of all philosophers, by means of experiments, sound demonstrations and discourses, Galileo convinced them of the falsity of many conclusions of Aristotle concerning the subject of motion, till then considered as very clear and indubitable; such as, among others, that the speed of moving objects of the same matter and of different weights, moving through the same medium, do not conserve the proportion of their gravity, assigned by Aristotle, but instead all move at the same speed, demonstrating this with repeated experiments performed from the top of the Bell Tower of Pisa in the presence of other lecturers and philosophers and of the entire student body».

The tower was also the site of an unsuccessful verification experiment conducted by Carlo Renaldini, a member of the Accademia del Cimento. He attempted several times «at the foot and at the top of the bell tower of Pisa», to verify the variation of the level of mercury according to altitude, but without succeeding «to obtain any fruit».