Pisa is a city in the Tuscany region of Central Italy. Pisa is known worldwide for its leaning tower. The tower is situated behind the Pisa Cathedral and is the third oldest structure in the city's Cathedral Square. The tower's tilt began during construction in the 12th century, 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 in the 14th century. It gradually increased until the structure was stabilized (and the tilt partially corrected) by efforts in the late 20th and early 21st centuries.
