January 1990: Tower closed to the public after 13th Century tower in Pavia collapsed, raising fears that Pisa would follow.
March 1990: Italian government appoints an international commission to save the tower - the 17th in the tower's history.
September 1990: Commission meets for the first time.
1991: Electrolevels installed on the tower to monitor movements.
1992: Lower tiers of the tower reinforced using galvanised prestessed tendons.
1993: 600 tonnes of lead placed on the tower's northern foundations to counter the lean achieve the first reverse in direction for 800 years: movement north of 50 arc seconds.
September 1995: Work to install reinforced concrete ring beam and ground anchors below the walkway around the base of the tower halted after tower lurches south. 270t of lead added to northern foundations.
1996: Soil excavation method of stabilisation agreed and trialled.
December 1996: Commission disbands after legal jurisdiction runs out.
March 1997: New Commission appointed with eight of 14 former members. Powers set to end 1998.
June 1997: New commission meets for the first time. Decision to use soil excavation questioned.
August 1998: Commission agrees to go forward with preliminary soil excavation trials.
December 1998: Funding agreed to pay for work during 1997 and 1998. Committee's legal jurisdiction over the tower expires.
December 1998: Cable stays attached to the tower as a precaution, before preliminary soil excavation trials.
July 1999: Preliminary soil excavation completed successfully.
September 1999: 23 tonnes of lead removed from foundations. Start of soil excavation delayed through lack of funding.
January 1999: Funding agreed and new law passed to allow work to continue to completion.
February: Planned start of final soil excavation.