Construction on the Tower of Pisa, which began in 1173, had reached only the third storey when architects noticed that the white-marble campanile (bell tower) was leaning.

Before serious attempts could be made to correct it, war broke out between the Italian city-states so building was halted for over a century. It wouldn’t be until the late-14th century that the tower was finally completed, but nothing had managed to right the lean.

Today, following extensive work, the Tower of Pisa is safe from toppling, but it will never stand fully straight – not that the millions of tourists who visit it every year would want it to. Here are 5 facts about the Tower of Pisa...


Short order

When building was stopped the first time, due to war, the tower was already leaning. The break, however, allowed the tower and its foundations to settle – without it, the tower would have probably collapsed.

The second phase of building commenced in 1272, and chief architect Giovanni di Simone attempted to correct the lean by making the next storey taller on the shorter side. This just made it heavier, which caused the tower to sink more.

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Step up

Two spiral staircases run to the top of the tower. Whereas one has 294 steps, however, the other has 296. It needed two extra to compensate for the height difference.


Save the tower

During World War II, it was thought that the Germans were using the tower as an observation post. US sergeant, Leon Weckstein, was about to order an artillery strike on the position, but – on seeing the beauty of the tower – chose not to.


The bell tolls

Over the years, seven bells were installed, the largest weighing 3,620kg. As restoration efforts gathered pace in the 20th century, however, they were silenced as it was believed that their movement made the lean worse.


Strengthening the structure

The design was flawed from the start. Despite plans for the tower to be 56 metres high, the foundations were only three metres deep initially. To make matters worse, the soil was unstable (the name Pisa, after all, comes from the Greek for ‘marshy land’).

At its worst, the lean was 5.5 degrees (about 4.5 metres). From 1990-2001, a major project removed earth from the taller side, which reduced the lean to under four degrees. It is thought the tower should now be stable for at least 200 years.

This content was first published in the January 2016 issue of History Revealed