Ponca City, We Love You writes "The tower of Pisa began to lean five years after its construction began, in 1178, and by 1990 it had tilted more than four meters off its true vertical. Conservationists estimated that the entire 14,500-ton structure would collapse 'some time between 2030 and 2040.' Now the Leaning Tower of Pisa has been stabilized and declared safe for at least another three centuries. The stabilization, which cost $30M, was accomplished by anchoring it to cables and lead counterweights, while 70 tons of soil were removed from the side away from the lean, and cement was injected into the ground to relieve the pressure. The tilt has now returned to where it was in the early 19th century. Nicholas Shrady, author of Tilt: A Skewed History of the Tower of Pisa, says that the tower was destined to lean from the outset because it was built on 'what is essentially a former bog.' Shrady adds that the tower previously came close to collapsing in 1838, 1934, and 1995. (The commission convened in 1990 to study the tower's stability was the 17th such.) Although Galileo Galilei is said to have dropped cannon balls from the tower in a gravity experiment, Shrady says the myth is the result of 'the overripe imagination of Galileo's secretary and first biographer, Vincenzo Viviani.'"