1990: Leaning Tower of Pisa closed to public

The Leaning Tower of Pisa has been closed to the public for the first time in 800 years amid speculation the structure is on the verge of toppling over.

Over the past 100 years the belfry at the top of the mediaeval tower has moved 9.6 inches (nearly a quarter of a metre).

The tilt is currently 16ft (4.9m) off the perpendicular and increases by about one-twelfth of an inch (2mm) every year because the layer of clay and sand on which it is built is softer on the south side than on the north.

So, the Italian government has set aside 100bn lire (£47m) and appointed an international team of experts to come up with a detailed plan within three months to save the building from collapse.

One million visitors

The 13th century monument, which took more than 200 years to build, attracts in excess of one million visitors each year, many of whom climb to the top to enjoy the panoramic view of Pisa.

The tower's closure is therefore bound to have a significant impact on the city's tourism industry.

The eight-storey structure began tilting almost immediately after it was completed in 1350 and although there are no plans to completely straighten it, experts believe urgent work is required to reverse the tilt.

Attempts have been made in the past to stop the building moving. Mediaeval builders tried to correct the tilt but their efforts resulted in the upper section of the tower leaning at a different angle to the lower section.

The Leaning Tower's ornate and unique exterior balconies were built to enable local dignitaries to be seen by the populace during religious processions in the Middle Ages.