Leaning Tower of Pisa is a bell tower at Pisa, Italy. It is famous for leaning 141/2 feet (4.4 meters) out of line when measured from the seventh story. It inclines because its foundation was built on unstable soil. Construction began in 1173 and ended between 1360 and 1370. The ground underneath the tower first started to sink after the first three stories were completed.
The tower, or campanile, is part of a complex of three buildings—a baptistery, a church, and the bell tower. Together the three structures form the Cathedral of Pisa, one of the world’s most beautiful building groups. While most cathedrals in Europe combine the baptistery, church, and tower in a single building, the Italians frequently separated them, as at Pisa. Built during the Romanesque period, the three buildings are noted for their colorful marble and decorative arches.
The tower is 51 feet (15.5 meters) in diameter and about 180 feet (55 meters) tall. The walls are 13 feet (4 meters) thick at the base and from 6 to 7 feet (1.8 to 2.1 meters) thick at the top. Fifteen arches surround the tower on the ground floor, and 30 arches encircle each of the next six stories. The top story, which houses the bells, has 12 arches. An inner staircase of almost 300 steps leads to the top. In 1990, the tower was closed for repairs. At that time, its lean had been increasing an average of 1/20 of an inch (1.3 millimeters) per year. Engineers stabilized the tower’s foundation and straightened it about 15 inches (38 centimeters) to prevent it from eventually collapsing. The tower was reopened to the public in 2001.
According to legend, the Italian physicist Galileo made his famous experiments with falling weights in 1589 from the top of the tower. But many scientists no longer believe this story.
