Ĭonstruction of the tower occurred in three stages over 199 years. A 2001 study seems to indicate Diotisalvi was the original architect, due to the time of construction and affinity with other Diotisalvi works, notably the bell tower of San Nicola and the Baptistery, both in Pisa. A piece of cast bearing his name was discovered at the foot of the tower in 1820, but this may be related to the bronze door in the façade of the cathedral that was destroyed in 1595. Pisano left Pisa in 1185 for Monreale, Sicily, only to come back and die in his home town. For many years, the design was attributed to Guglielmo and Bonanno Pisano, a well-known 12th-century resident artist of Pisa, known for his bronze casting, particularly in the Pisa Duomo. There has been controversy surrounding the identity of the architect of the Leaning Tower of Pisa. The structure was stabilized by remedial work between 19, which reduced the tilt to 3.97 degrees. By 1990, the tilt had reached 5.5 degrees. It worsened through the completion of construction in the 14th century. The tower began to lean during construction in the 12th century, due to soft ground which could not properly support the structure's weight. The tower has 296 or 294 steps the seventh floor has two fewer steps on the north-facing staircase. Its weight is estimated at 14,500 tonnes (16,000 short tons). The width of the walls at the base is 2.44 m (8 ft 0 in).

The height of the tower is 55.86 metres (183 feet 3 inches) from the ground on the low side and 56.67 m (185 ft 11 in) on the high side.

The tower is one of three structures in the Pisa's Cathedral Square ( Piazza del Duomo), which includes the cathedral and Pisa Baptistry. It is known for its nearly four-degree lean, the result of an unstable foundation. The Leaning Tower of Pisa ( Italian: torre pendente di Pisa), or simply, the Tower of Pisa ( torre di Pisa ), is the campanile, or freestanding bell tower, of Pisa Cathedral.

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