The Leaning Tower of Pisa (Italian: Torre di Pisa) is the campanile, or bell tower, of the Italian city of Pisa's cathedral. The tower was intended to stand vertically, but began leaning soon after construction started in August of 1173.

The height of the tower is 55 metres from the ground. Its weight is estimated at 14,500 tonnes. The current inclination is about ten percent. The tower has 296 steps.

History

The construction of the Tower of Pisa began in 1173. Only in 1372 was the last floor built and the bell installed.

Galileo Galilei is said to have dropped two cannon balls of different masses from this tower to demonstrate their descending speed was independent of their mass. This story is widely considered to be apocryphal.

During World War II, the US army destroyed nearly all towers in Pisa due to the potential threat from snipers. The Leaning Tower was scheduled to be blown up as well; fortunately, a last-minute order to retreat prevented the destruction.

On February 27, 1964, the government of Italy requested aid in preventing the tower from toppling. A multilateral task force of engineers, mathematicians and historians was assigned and met on the Azores islands to discuss stabilization methods. After many decades of work on the subject, the tower was closed to the public in January 1990. After a decade of corrective reconstruction and stabilization efforts the tower was reopened to the public on June 16, 2001.

At least two people have jumped down the tower with a parachute; Mike McCarthy on August 5, 1988, and Arne Aarhus on February 1, 2000.

See also

• Leaning tower, for a general description of the phenomenon.