Leaning Tower of Pisa

Leaning Tower of Pisa, the campanile, freestanding bell tower, of the cathedral of Pisa, Italy. Like the cathedral and associated baptistery, the tower was built in the Romanesque style (see Romanesque Art and Architecture). Adjacent to the three structures is a cemetery, or camposanto (Italian: literally, holy field, originally meant to hold sacred soil from the holy land).

The tower is renowned for its marked tilt. This spectacular irregularity has tended to obscure the fact that it is also a magnificent example of Romanesque architecture and decoration. Begun in 1173, the eight-story round tower is 55 m (180 ft) tall and 16 m (52 ft) in diameter at the base. The ground floor is encircled by a blind arcade, or series of walled-in arches. Six additional levels of open galleries, consisting of round arches supported on columns, are surmounted by the bell chamber, somewhat smaller in diameter. Although the tower's ancient bells remain in place, they are no longer rung. The interior of the tower is occupied by a 294-step spiral staircase that leads to the bell chamber. The exterior is adorned with fine multicolored marbles and excellent carved work. The doorway, which is especially ornate, features grotesque carvings of animals.

Construction of the campanile stretched over a period of nearly 200 years, partly because of delays caused by the tower's persistent structural problems. By the time the first three stories were completed, one side of the tower had already begun to sink into the soft soil, and construction was halted for nearly 100 years. The first attempts to counter the lean of the structure were made in 1275, when construction resumed. By 1301 six stories were complete, and the tower was finished about 1350.

At its summit, the structure tilts about 5 m (16 ft) from the vertical, and the lean is said to be increasing at a rate of about 1 mm (about 1/25 of an inch) per year. Italian physicist Galileo conducted his famous experiments with gravity and the relative speed of falling objects from the top story of the tower. The structure has been closed to the public since 1990 due to safety and conservation concerns.