The iconic Leaning Tower of Pisa loses its tilt by another 1.6 inches

The symbolic imagery of tourists holding the tilt of Italy's leaning tower of Pisa while posing for photographs may not remain as pose-worthy in the times to come. Because the leaning tower of Pisa is losing its tilt.The site holds a remarkable significance for the fact that at the end of thesixteenth century, Physicist-mathematician Galileo dropped two spheres of different masses from the top of the tower to demonstrate that mass doesn't affect the descent of objects, an idea mathematically furthered by Newton a century later.

But after witnessing nearly centuries-long developments inscience, history and archaeology, the tower is losing its tilt due to stabilisation works. Slowly but steadily, it's moving upright.

An 11-year stabilisation project reduced the tower's lean by 15 inches by 2001, and in the 21 years since, the tower has straightened itself by another 1.6 inches (4cm), according to a study funded by the preservation organisation Opera Primaziale della Pisana (OPA).

While the tilt has been reduced, it still sways at an average of about 0.02 inches (0.5 mm) a year, according to professor of geotechnics Nunziante Squeglia from the University of Pisa.

"Although what counts the most is the stability of the bell tower, which is better than expected," he told Italy's National Associated Press Agency (ANSA).

An OPA spokesperson also told ANSA: "Considering it is an 850-year-old patient with a tilt of around five metres and a subsidence of over three metres, the state of health of the Leaning Tower of Pisa is excellent."

Theories suggest that the 57 metre (186-feet) tower began to sink after construction, which started in 1173.

The cause was due to a flawed design which meant it had a foundation that was only three-metres deep and was set in weak, unstable subsoil.

The build wasn't completed until 1319 due to various battles between Pisa and Genoa, Lucca and Florence, but these pauses did give the underlying soil time to settle.

Fast forward to 1990, the tower was still tilting 5.5 degreesouthwards, and was closed to the public in fear it would crumble.

By 2001, a conservation effort had straightened up the tower by 15 inches (38 cm), or 0.5°, and it has continued to straighten itself ever since.

Experts pronounced it would be safe for the next 300 years during a health check in 2005, according to ANSA. Italian media also cited the experts saying that advances in technology will mean the tower will one day straighten up completely.

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