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The Tower of Pisa

Leaning and Lopsided Buildings: The Tower of Pisa

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The Tower of Pisa in Pisa, Italy is one of the world's most famous leaning buildings.
Leaning Tower of Pisa in Pisa, Italy

Leaning Tower of Pisa in Pisa, Italy

Photo (cc) Flickr Member "M4rvin"

About the Leaning Tower of Pisa

Other Names: Torre Pendente di Pisa, Torre di Pisa (Tower of Pisa)
Location: Piazza dei Miracoli (Miracle Square), Pisa, Italy
Built: 1173-1370
Height: 191 1/2 feet (58.36 meters) at the foundation
Architect: Unknown. The tower may have been designed by Bonanno Pisano and Guglielmo of Innsbruck, Austria or Diotisalvi
Style: Romanesque
Construction Description: "...a cylindrical stone body surrounded by open galleries with arcades and pillars resting on a bottom shaft, with the belfry on top. The central body is composed of a hollow cylinder with an outer facing of shaped ahlars in white and grey San Giuliano limestone, an interior facing, also made of textured verrucana stone, and a ring-shaped stone area in between...."
Outer Diameter: 64 feet (19.58 meters) at foundation
Width of Center Hole: 14 3/4 feet (4.5 meters)

The Tower of Pisa was designed as a bell tower (campanile) but its main purpose was to visually attract people to the cathedral in the town of Pisa. The foundation of the tower was only three meters thick and the soil underneath was unstable. A series of wars interrupted the construction for many years. During the long pause, the soil continued to settle. Rather than abandon the project, builders accommodated the tilt by adding extra height to the upper stories on one side of the Tower. The extra weight caused the upper part of the Tower to lean in the opposite direction.

Over the centuries there have been many attempts to remove or reduce the tilt. In 1990, an Italian government-appointed special commission determined that the tower was no longer safe for tourists, closed it off, and started devising ways to make the building safer.

John Burland, a professor of soil mechanics, came up with the system of removing soil from the north side in order to make the building settle back into the ground and thus reduce the tilt. This worked and the tower was reopened to tourism in 2001.

Today, the restored Tower of Pisa leans at a 3.97 degree angle.

Learn More:

Source: Miracle Square, Leaning Tower, Opera della Primazial Pisana [accessed January 4, 2014]

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