Begun in 1174 as a campanile (bell tower) for the cathedral complex, the leaning tower of Pisa has become famous for its tilt of 3.9 meters from the perpendicular due to the uneven settling of its foundations.
When its lean became noticeable on the completion of its third storey, the engineer, Bonnano Pisano, compensated by increasing the height of its storeys on the short side. He was unsuccessful and the tower sank even further. Although work was stopped several times, the tower was eventually completed in the fourteenth century and although in this century the foundations have been strengthened, the tower is still in grave danger of falling.
Like the rest of the cathedral complex, the tower is built of white marble in a blend of Romanesque and Gothic styles typical of Pisa. An unsupported legend has it that Galileo developed his theories on falling bodies by dropping weights from the tower to the ground.