Colosseum in need of urgent support as one side is 15 inches lower than other

The Colosseum could be in need of the kind of structural intervention that saved the Leaning Tower of Pisa after officials found that its south side is 15 inches lower than the north.

Authorities became aware of the tilt in the 2,000-year-old amphitheatre about a year ago and have been monitoring it closely for the past couple of months.

They believe that "dynamic vibrations" caused by Rome's heavy traffic, may be responsible for the drop on the south side next to one of Rome's busiest thoroughfares.

Now experts from Rome's Sapienza University and the Institute of Environmental Geology and Geoengineering (IGAG) have been asked to conduct an urgent scientific study to determine the cause.

Professor Giorgio Monti, from Sapienza's department of structural engineering, said he fears there may be a crack in the base of the monument.

"The concrete foundation on which the Colosseum is built is an oval-shaped 'doughnut' which is 13 metres [42 feet] thick," ProfMonti said. "There could be a stress fracture inside it."