Who designed the Leaning Tower of Pisa?Historians and other experts are still debating who the architect of the Leaning Tower was. For a long time, it was accepted that the design was by Guglielmo and Bonanno Pisano, whose name was found on a piece of material at the base of the tower. A more recent study in 2001 points to Diotisalvi as the original architect since the Leaning Tower has a lot in common with his other works in Pisa that date to the same time, including the Baptistery and the bell tower of San Nicola. In any case, the tower was built over 199 years and was worked on by several different architects before it was completed in 1372.
Why does the Leaning Tower lean?The tower was built on soft ground composed of clay and fine sand, and originally its foundations were less than 10 feet (3m) deep. The tilt became obvious in the early stages of building as the foundation couldn’t compensate for the soft ground, and for a long time construction was put on hold - partly because of the tilt, but mostly because Pisa was involved in a lot of wars with its neighbors. By the time construction resumed, the building had mostly stabilized, but over the centuries the tower gradually leaned more and more in one direction. In the late 19th and early 20th centuries, the tower was stabilized. Today the tilt is about 3.97º, but before the stabilizing efforts of the last centuries, it was 5.5º.
Is it the most crooked building in the world?Since 2007 the Leaning Tower of Pisa has had to give up its crown as the most crooked building in the world to the church of Suurhusen in Eastern Friesland in Germany. The Guinness Book of Records lists the church as having a tilt of 5.19º, which is much more dramatic than the Leaning Tower’s current 3.97º. Apart from accidentally wonky buildings, there’s a skyscraper in Abu Dhabi, called Capital Gate, which was deliberately built to have a tilt of 18º. But the Leaning Tower of Pisa is definitely the best known and is a much-loved photo opportunity for tourists from around the world!
Could the Leaning Tower fall over?After the most recent work to stabilize the tower, in particular, the removal of 70 tonnes of earth in 2008, the tower should barely move for the next 200 years. Visits to the tower are therefore totally safe and won’t cause damage either to the building (or the visitor!). Measures taken to make sure that the tower is safe include the placement of lead weights, the addition of an extra concrete ring around the base of the tower, and the use of anchored steel ropes. Since 1280 the tower has survived 4 strong earthquakes, and its survival is due to the soft earth which has caused its distinctive look - while the rest of the earth moves, the tower’s unique characteristics and soft foundations mean it doesn’t resonate with the ground motions caused by earthquakes.
It was built as a bell tower, but does it still have bells?Yes! The Leaning Tower is home to 7 bells. Its most famous bell, Pasquareccia, was older than the Leaning Tower itself. It used to ring from the Palazzo Pretorio, where it was known as La Giustizia and tolled to announce the executions of traitors and criminals. It was replaced by a replica at the end of the 18th century. The bells ring daily to announce masses at Pisa Cathedral.
How many stairs go to the top of the Leaning Tower? Is there an elevator?There is no elevator to the top of the Leaning Tower of Pisa, and children under the age of 8 aren’t allowed to climb the stairs for safety reasons. There are 296 stairs to the top, some of which are in a tight spiral. It takes about 30 minutes to complete the climb and descent.
Did Galileo really throw heavy things off the top of the Leaning Tower?Galileo’s student Vincenzo Viviani wrote in his biography that Galileo dropped balls of identical material but different masses off the top of the Leaning Tower of Pisa. This experiment demonstrated that objects fall at the same pace, regardless of their mass, and was a key contradiction of Aristotle’s teaching. While it’s a nice story and lets students picture the scientific principles visually, there’s no evidence that it really happened. Most historians believe it was a thought experiment. A similar experiment was carried out by Flemish scientists Simon Stevin and Jan Cornets de Groot in the church tower in Delft.