Leaning Tower (Italy)

Leaning Tower of Pisa is a bell tower at Pisa, Italy. It is famous for leaning 4.4 meters out of line when measured from the seventh story. It was built to stand vertically but began leaning soon after construction started in August 1173. It tilts because its foundation was built on unstable soil. The ground beneath the tower first started to sink after the first three stories were built.

The height of the tower is 55.86 m (183.27 ft) from the ground on the low side and 56.70 m (186.02 ft) on the high side. The width of the walls at the base is 4.09 m (13.42 ft) and at the top 2.48 m (8.14 ft). Its weight is estimated at 14,500 metric tons (16,000 short tons). The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase. Prior to restoration work performed between 1990 and 2001, the tower leaned at an angle of 5.5 degrees, but the tower now leans at about 3.99 degrees. This means that the top of the tower is displaced horizontally 3.9 metres (12 ft 10 in) from where it would be if the structure were perfectly vertical.

A popular tourist activity is to pose for photographs pretending to "hold up" the leaning tower and preventing it from falling. The illusion is created through the principle of forced perspective.

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