The Leaning Tower of Pisa

Key dates in the history of the Tower of Pisa.

1173 Construction begins.
1178 Construction is halted.
1272 Construction resumes.
1278 Construction is halted again.
1298 The first commission to study the Tower’s lean is convened.
1370 Construction officially completed.
1838 Architect Alessandro della Gherardesca excavates a walkway around the Tower, flooding the base of the campanile and destabilizing the structure.
1934 Italian dictator Benito Mussolini sanctions a plan to inject 90 tons of cement into 361 holes at the base, which nearly topples the Tower.
1990 The Tower is closed to the public and the 17th commission to study the Tower’s lean is convened.
1995 During the installation of underground stabilizing cables the Tower nearly collapses.
1999 Using a process known as soil extraction, engineers begin work on a long-term solution to promote the Tower’s stability.
2001 The Tower re-opens to the public.