Pisa is famous around the world for its famous leaning tower. But do you know what is the reason for this inclination?
The one known as the Tower of Pisa is actually the bell tower of the Cathedral of Our Lady of the Assumption. Located on the Piazza dei Miracoli , Piazza dei Miracoli in its original version, it is the most famous and most photographed monument in Pisa . Difficult to go to Tuscany without making a hike through this small town and its UNESCO World Heritage Site.
The tower whose first stone was laid in 1173 is the main reason why tourists flock to Pisa which it is the emblem. Beyond its beautiful Romanesque architecture the success of this monument is due to its astonishing inclination. Have you ever wondered why the tower of Pisa is leaning? Here are some answers.
The construction of the tower in question
The tower of Pisa is currently bent a little over 3 degrees to the south. If the angle of inclination was not always the same, the monument began to lean very shortly after being erected.
Photo credit: Flickr – Softeis
It is indeed the very characteristics of the terrain that are involved and that from the start have tilted the campanile. It was built on an alluvial plain that is alluvium (old sediments, debris), a soil rich in water that can cause land subsidence . It would then be a sedimentary rock called marne, sensitive to water and favoring slope instabilities, which would explain why the tower of Pisa is tilted. Other hypotheses evoke a lack of foundation.
A tower that never stops moving
Continuing to slowly subside, the tower of Pisa had to be closed to the public in 1990. Important work was then undertaken in 1993 in order to secure the building. Blocks of lead on the ground, braces to try to stop the collapse, micro-excavation on the northern part of the foundations, everything had been done to save the campanile that was then thought doomed to fall.
The lead counterweights on the Leaning Tower of Pisa in 1998 – Photo credit: Wikimedia – Rolf Gebhardt
The work proved to be profitable since in 2003 the tower had recovered 50 cm of its inclination is the aspect that it could present at the end of the XVIIIth century. More surprising, experts noted that between the end of the work and 2013 the campanile had recovered by itself 2.5 cm of inclination. It seems that after leaning for hundreds of years the tower of Pisa suddenly decided to recover!
This spontaneous movement of turn recovery is actually the consequence of the interventions started in 1993. In both directions it seems that the tower of Pisa has not finished moving and make us turn our heads!
Main photo credit: Flickr – Andy Hay