History of the Leaning Tower of Pisa
It took 3 phases and 177 years to build the Tower of Pisa. The architect Bonanno Pisano began construction in 1173 and erected the first floor surrounded by 15 white marble columns with classical capitals and blind arches. During the construction of the third floor in 1178, the tower tilted 5 cm to the south-east due to the unstable ground on which it was built, and construction was stopped. This phase was important as the ground had to settle down, otherwise the tower would have collapsed.
100 years later, Giovanni di Simone resumed work and tried to compensate for the imbalance by building four vertical floors. However, the result was not as expected, the bell tower was still leaning and the work was therefore stopped again. In 1298 a pluvimetric deviation of 1.43 m was measured, 60 years later this figure had risen to 1.63 m. Tommaso Pisano continued the construction of the bell tower and completed its construction in 1372. According to Vasari, this work is the work of Nicola Pisano and his son Giovanni.