Italy's Leaning Tower of Pisa

The Leaning Tower of Pisa is the freestanding bell tower, of the cathedral of the Italian city of Pisa. It is situated behind the Cathedral and it is the third structure by time in Pisa's Piazza del Duomo (Cathedral Square).

Although intended to stand vertically, the tower began leaning to the southeast soon after the onset of construction in 1173 due to a poorly laid foundation and loose substrate that has allowed the foundation to shift direction. The tower presently leans to the southwest.

The height of the tower is 183.27 ft from the ground on the lowest side and 186.02 ft on the highest side. The width of the walls at the base is 13.42 ft and at the top 8.14 ft. Its weight is estimated at 14,500 tons. The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase. The tower leans at an angle of 3.97 degrees. This means that the top of the tower is 13 ft from where it would stand if the tower were perfectly vertical.

A nighttime photo of the Duomo and the Leaning Tower of Pisa.

Photo courtesy Parametricformations

The Tower of Pisa was a work of art, performed in three stages over a period of about 177 years. Construction of the first floor of the white marble campanile began on August 9, 1173, a period of military success and prosperity. This first floor is surrounded by pillars with classical capitals, leaning against blind arches.

The tower began to sink after construction progressed to the third floor in 1178. This was due to a mere three-meter foundation, set in weak, unstable subsoil. This means the design was flawed from the beginning. Construction was subsequently halted for almost a century, because the Pisans were almost continually engaged in battles with Genoa, Lucca and Florence. This allowed time for the underlying soil to settle. Otherwise, the tower would almost certainly have toppled. In 1198, clocks were temporarily installed on the third floor of the unfinished construction.

In 1272, construction resumed under Giovanni di Simone, architect of the Camposanto. In an effort to compensate for the tilt, the engineers built higher floors with one side taller than the other. This made the tower begin to lean in the other direction. Because of this, the tower is actually curved. Construction was halted again in 1284, when the Pisans were defeated by the Genoans in the Battle of Meloria.

The seventh floor was completed in 1319. The bell-chamber was not finally added until 1372. It was built by Tommaso di Andrea Pisano, who succeeded in harmonizing the Gothic elements of the bell-chamber with the Romanesque style of the tower. There are seven....(read more at Wikipedia)

The famous Leaning Tower of Pisa has stopped moving for the first time in its 800-year history and it should remain so for the next 300 years.

Engineers are confident that their hard work of more than 10 years to rescue the Leaning Tower of Pisa has been successful and should be stable for at least three centuries. All of our best hopes have been confirmed. We can now state that the tower will not move again for at least three centuries, said Michele Jamiolkowski, a Turin-based engineer who led the project.

Currently, the tower leans 13 feet off center, and has been straightened by 14.5 inches since 1999 with the help of a 40 million dollar restoration project. The tower, which has been leaning almost since building work first began in 1173, was closed to the public in 1990 because of safety concerns. The 183-foot tower was nearly 15 feet off vertical and its structure was found to have been weakened by centuries of strain.

Unless noted, photos are courtesy Creative Commons.