The most fascinating fact about the Leaning Tower of Pisa is that its construction took nearly 200 years, spanning three distinct phases from 1173 to 1372. This lengthy process, interrupted by wars, was unintentional but crucial; the pauses allowed the unstable subsoil to settle, which almost certainly prevented the tower from collapsing entirely during its construction.
Why does the Tower of Pisa lean?
The Leaning Tower of Pisa leans because it was built on soft, unstable subsoil—a dense mixture of clay, sand, and shells—incapable of supporting the structure's immense weight. The foundation, a mere three metres deep, was flawed from the start. The tilt began to show in 1178 after construction reached the third storey, just five years after it began.
Key Facts and Figures
Pisa's famous campanile (bell tower) is more than just a quirky photo opportunity. Its history and dimensions are a testament to centuries of engineering challenges and solutions. Here are some of the most important stats:
- Height: The tower stands at 55.86 metres (183.3 feet) on its low side and 56.67 metres (185.9 feet) on its high side.
- Weight: It has an estimated weight of 14,500 metric tonnes (16,000 short tons).
- Number of Steps: There are 296 steps to the top via the south-side staircase and 294 on the north side.
- The Lean: Before restoration work in the 1990s, the tilt reached a dangerous 5.5 degrees. Today, it is stable at about 3.97 degrees from the vertical.
- Construction Time: The tower was built in three stages over 199 years, from 1173 to 1372.
More Surprising Tower of Pisa Facts
1. It's not the only leaning tower in Pisa
The soft subsoil that caused the famous tower to tilt affects the whole area. Pisa has several other leaning towers, including the bell tower of the Church of St. Michele degli Scalzi and the bell tower at the Church of St. Nicola. The city's name is believed to derive from a Greek word for "marshy land," hinting at the unstable ground beneath.
2. The architect is still a mystery
The identity of the original architect is a subject of debate. For many years, the design was attributed to Bonanno Pisano, but others suggest Diotisalvi, who designed the nearby Baptistery. A stone inscription with Pisano's name was found at the base in 1820, but it's not conclusive proof he was the architect.
3. Engineers made the tower curved on purpose
When construction resumed in 1272 under Giovanni di Simone, engineers tried to compensate for the lean. They intentionally built the upper floors with one side taller than the other, giving the tower its characteristic curve. This effort, however, caused the centre of gravity to shift and made the structure sink even more.
4. It has seven very heavy bells
The bell chamber at the top houses seven bells, one for each note of the musical major scale. The largest bell, L'Assunta, weighs a massive 3,620 kg (7,981 lbs). Due to fears that their movement could worsen the lean, the bells are no longer rung by swinging them; instead, electromagnetic hammers strike them.
5. Galileo Galilei may have used it for an experiment
According to a biography written by his pupil, Pisa-native Galileo Galilei is said to have dropped two cannonballs of different masses from the top of the tower. He did this to demonstrate that their speed of descent was independent of their mass. While this is one of the tower's most famous tales, it remains a legend as there is no definitive proof it happened.
6. It was closed to the public for over a decade
By 1990, the tower's lean had reached 5.5 degrees, and authorities feared it was on the verge of collapse. The tower was closed to the public on January 7, 1990, for an extensive stabilisation project. It remained closed for 11 years, reopening on December 15, 2001, after the tilt was reduced to a safer angle.
7. An Allied soldier saved it in World War II
During World War II, the Allies suspected the Germans were using the tower as an observation post. A U.S. Army sergeant, Leon Weckstein, was sent to confirm this and call in an artillery strike. However, he was so impressed by the beauty of the tower and the Square of Miracles that he deliberately refrained from ordering the strike, saving it from destruction.
Frequently asked questions
How many steps are in the Leaning Tower of Pisa?
There are 296 steps on the south staircase and 294 on the north staircase. The two-step difference is because the seventh floor is shorter on the north-facing side.
How long did it take to build the Tower of Pisa?
Construction occurred in three stages over 199 years. Work began in August 1173 and the bell chamber was finally completed in 1372.
Is the Tower of Pisa still leaning?
Yes, the tower still leans, but it is stable. A major restoration project between 1990 and 2001 reduced the tilt from 5.5 degrees to its current 3.97 degrees. Engineers have declared it will be stable for at least another 200-300 years.
Ready to see this architectural marvel for yourself? You can explore the history and climb the famous spiralling steps when you book tickets in advance to secure your spot.