The stabilization works for the Tower began in the year 1990 and it took an entire decade to recover some of its inclination.
From over 5°, the lean was brought back to less than 4°. This is considered to be a safe inclination and experts say the Tower can now stand 200 more years without any further intervention.
The stabilization works to fix the Tower were led and coordinated by a group of brilliant minds. Here are the most relevant names...

 

With the top inclination registered at 5.5° in 1993, the Tower was really at risk of collapse and it was in desperate need of a fix. The straightening works recovered over 40cm of lean (measured at the top). The last known inclination reading is from 2013 (12 years after the end of the works,) and the building straightened up other 2.5cm. Experts say that it is still stabilizing (read more: why the Tower does not fall).

It takes more than one single person to do something as grandiose as straightening the Leaning Tower. It took in fact 10 years and a commission of 13 experts.

With the top inclination registered at 5.5° in 1993, the Tower was really at risk of collapse.

The commission of 13 that delivered this outstanding result was hired by the "Opera della Primaziale Pisana" (the legal entity who owns the Tower) and each expert was subject to the approval of the Italian Government and of the Church.

Among the 13 persons in the commission of experts, a few names stood out:

the British Prof. John Burland; 
the French Architect Jean Barthélémy;
the Polish Prof. Michele Jamiolkowski;
the Italian Prof. Salvatore Settis.

Prof. John Burland was the one to lead the 30 million EUR project to its successful implementation.
Burland, Emeritus Professor and Senior Research Investigator at the Department of Civil and Environmental Engineering of Imperial College London, had extensive experience in working with soft soils subject to deformation. He previously "saved" the London's Big Ben when it was about to topple over due to nearby excavation works for the Jubilee Underground line.
He was the perfect man for the job.

There all proven to be the right persons and also the timing was about the best it could have been.
Salvatore Settis, president of the commissionthat fixed the Tower, declared "if we had not stepped in, the Tower would have collapsed between 2030 and 2040".

Burland directed the works from his office in London. Every day he used to receive a fax with the last readings of inclination of the Tower, along with other measurements. He then used to give precise instruction to the on-site crew.
15 years later it all seems unrealistic: in an age ruled by instant messaging and live video streaming, saving the Tower thanks to a fax is something that feels somehow antiquated... and still, they did it.

Today we can still admire the Tower in all its beauty thanks to this brave group of people that put their reputation on the line to save the monument.

..if we had not stepped in, the Tower would have collapsed between 2030 and 2040

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