The scene of countless tourists' Instagram pics "pushing" the leaning tower back up, the Leaning Tower of Pisa is today one of Italy's most famous landmarks. The tower itself is a campanile or freestanding bell tower part of the city's cathedral. Today it stands (or leans) as the third-oldest structure in Pisa's Cathedral Square. The tower is constructed of white marble and even with its foundation engineering flaws is a testament to medieval Italian engineering.

THETRAVEL VIDEO OF THE DAY

Today, it is one of Italy's most famous landmarks and has even been granted UNESCO World Heritage status - not bad for an engineering screw-up. It is one of the great medieval structures that can be seen throughout Italy and Europe today.

History Of The Leaning Tower Of Pisa

The Leaning Tower of Pisa was never meant to lean. That is the result of an unstable foundation.

Leaning Tower Of Pisa: The Facts

  • Height: 183 Feet or 56 Meters On the Low Side And 186 Feet Or 56.5 meters From The High Side
  • Number Of Steps: 296 or 294
  • Max Lean: 5.5 Degrees 1990 (Now 3.97 After Remedial Work)
  • Start of Construction: 1173
  • Country: At The Time The Republic Of Pisa
  • Number of Years To Complete: Around 200 Years (With Extensive Hiatuses)

The tower's foundation was always unstable and it began to lean while it was still under construction during the 12th century. The ground was just too soft for the weight of the building and the foundation hadn't been prepared accordingly. After construction, it continued to lean more and reached 5.5 degrees in 1990.

  • Part Of: Complex Of Square Of Miracles

The tower is part of a much larger complex that was built to flaunt the wealth and military victories of Pisa. The complex of which it is a part is called the Piazza Dei Miracoli (that is "The Plaza or Square Of Miracles"). The complex includes the baptistery, cathedral, cemetery, and this tilting bell tower.

The construction was not straightforward, not only because of its shifting foundations, but also because of Pisa's wars with Florence, Genoa, and Lucca. At that time the city of Pisa was the Republic of Pisa and was in near-constant warfare. These conflicts caused a 100-year hiatus in construction, the upshot is that the century-long pause enabled the foundation to settle. See here for what to see in the stunning city of Florence.

Related: 10 Etiquette Tips To Know Before Traveling To Italy

The engineer in charge when construction recommenced was Giovanni di Simone. He tried to compensate for the lean by making the tower's a little taller on the short side. This turned out to be counterproductive as the extra weight of the masonry just made it tilt and sink further. Over the next four centuries, the bells were installed, eventually, a total of seven balls were installed. Some of them were silenced in the 20 century out of a fear that these heavy bells' movement would worsen the lean.

  • Bell's Weight: The Heaviest Leaning Tower Of Pisa's Weight Is 8,000 Pounds or 3,600 Kg.

Despite a center of gravity giving headaches to engineers, the tower has survived multiple earthquakes. Ironically, that is due to the same stable soil on which it is built. A phenomenon is known as dynamic soil-structure interaction.

Lean And Repair Work

class="sc-1ndygth-0 kZykvr">

class="sc-1huk9pj-0 extIxd">

Over the course of the next 600 years, the lean continued at an annual rate of around .05 inches per year. The collapse was only a matter of time as the bell tower's center of gravity continued to move perilously outward. In 1990 engineers worked to stabilize the structure and reduce its dangerous lean. The first compensation work was done by injecting cement grout into the foundations and with various other types of bracing and reinforcements before the extensive work in the 1990s. After the work in the 1990s and the foundation settled, sensors in 2008 showed that the bell tower's movement had finally stopped.

Related: How To Best Plan A Trip Around Italy, If You Only Have A Week To Visit

The Leaning Tower And Galileo Galilei

One of the most famous scientific experiments conducted on the tower was that of Galileo Galilei who is said to have dropped two cannonballs from the tilting tower. These cannon balls  were of different masses and the experiment was to demonstrate that the rate of fall is independent of their mass. This is known as the law of free fall (a lead weight and a feather will fall at the same rate in a vacuum).

Surviving World War Two

The iconic tower had a close call during World War Two. During the Italian Campaign the Allies thought that the Germans were using the tower as an observation post, but seeing the beauty of the cathedral, they decided not to call in an artillery strike. Unfortunately, the same was not true of the Allied bombing and destruction of the stunning Monte Cassino in Italy in what was called "a colossal blunder … a piece of a gross stupidity."

Next: Where To Go On A First-Time Italy Trip, And What To Know Before You Do