The foundations of the tower have become unstable due to shifting soil. Over the following 800 years, it became evident that the 55-meter tower was not only learning, but also dropping at a pace of one to two millimeters every year. The Pisa Leaning Tower is now more than five meters off perpendicular.
The first record of the leaning of the Leaning Tower of Pisa comes from 1322. At that time, the tower was already falling as much as 1.5 meters per century. In 1772, an official measure showed that the tower was leaning by about 6 inches (15 centimeters). Since then, engineers have been working to secure the foundation and bring back the tower to balance.
The original tower was built between 1173 and 1194 as part of a new town called "La Peninsola" (the Peninsula). It was designed by Giorgio Pisano, who also designed the famous cathedral in Pisa. The tower was built using red Roman bricks that had been taken out of another unfinished building project in Italy. The weight of the tower was supposed to be supported by eight other similar towers around it, like a star when placed in a circle. But this plan was changed when it was found out that there was no enough sand on the peninsula for such large structures. So instead, the builders used big rocks as support against the wind, which can still be seen under the tower today.
The tower was stabilized as a result of restoration work completed between 1999 and 2001. Engineers placed weights on the structure's north end while removing earth from below, forcing it to sink back in that direction gradually. The Leaning Tower of Pisa still leans south, although at just 3.99 degrees. It is the only medieval European tower to be saved from destruction.
In response to the threat it poses to pedestrian safety, the city has installed an elevator inside the tower which allows visitors to climb to the top.
Engineering has also been used to try and prevent the tower from falling down entirely. In 1980-1981, architects Antonio Sant'Elia and Giuseppe Pieragostini added a small room on the first floor with windows looking out over the campo di Pisano (Pisan square). The room serves as a museum where visitors can see examples of medieval and early Renaissance art that were removed from the tower when it was restored in the 1960s.
You may have seen images of the tower online or in newspapers. They are often used in articles about Pisa because of its precarious state. In fact, the tower is not even close to being unsafe anymore. But since it is such a famous monument, people get worried when they see it leaning this way or that.
The tower remains a popular destination for tourists who visit Pisa every year.
Approximately a 10 degree angle The Tower of Pisa is 60 meters tall and leans at a 10 degree inclination till 1990. Despite being meant to be exactly vertical, it began to tilt during construction. The cause is not clear but may have been due to soil instability beneath the foundation.
The tower has been called Europe's tallest building site safety hazard because the structure is so unstable that its builder, Guilio de' Medici, had to hire workers to take measurements on the ground using ropes tied to the tower every morning before they went to work. If the tower fell over now, these workers would be in danger.
The first evidence of damage to the base of the tower comes from 1194 when parts of it collapsed. In 1272 the remaining parts of the base collapsed again. In 1364 another part of the base collapsed causing the tower to lean even more. In 1401 yet another part of the base collapsed bringing the total amount of damage to the base of the tower to over 100 incidents in just over 200 years.
In 1990 the tower was studied by Italian scientists who concluded that the tower was leaning at about 10 degrees to the ground. They also estimated that by 2050 the tower will have completely collapsed due to further erosion caused by the accumulation of water near its base.