The Leaning Tower of Pisa was originally used as what?

The Leaning Tower of Pisa  or simply the Tower of Pisa  is the freestanding bell tower, of the cathedral of the Italian city of Pisa, known worldwide for its unintended tilt. The tower's tilt began during construction, caused by an inadequate foundation on ground too soft on one side to properly support the structure's weight. The tilt increased in the decades before the structure was completed and gradually increased until the structure was stabilized (and the tilt partially corrected) by efforts in the late 20th and early 21st centuries.

Construction of the tower occurred in three stages over 199 years. Work on the ground floor of the white marble campanile began on August 14, 1173 during a period of military success and prosperity.  The seventh floor was completed in 1319. The bell-chamber was finally added in 1372. It was built by Tommaso di Andrea Pisano. There are seven bells, one for each note of the musical major scale. The largest one was installed in 1655.

After a phase (1990–2001) of structural strengthening, the tower is currently undergoing gradual surface restoration, in order to repair visible damage, mostly corrosion and blackening. These are particularly pronounced due to the tower's age and its exposure to wind and rain. In May 2008, engineers announced that the tower had been stabilized such that it had stopped moving for the first time in its history. They stated that it would be stable for at least 200 years.