Leaning Tower of Pisa
The height of the tower is 55.86 meters (183.27 feet) from the ground on the low side and 56.67 metres (185.93 feet) on the high side. The width of the walls at the base is 2.44 m (8 ft 0.06 in). 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.
The tower began to lean during construction in the 12th century, due to soft ground which could not properly support the structure’s weight, and it worsened through the completion of construction in the 14th century. By 1990 the tilt had reached 5.5 degrees.
At least four strong earthquakes hit the region since 1280, but the apparently vulnerable Tower survived.