Like the Tower of Pisa, Rome's Colosseum is starting to lean

"While stands the Coliseum, Rome shall stand; When falls the Coliseum, Rome shall fall; And when Rome falls -- the World."

If the Venerable Bede (673-735), the Anglo-Saxon monk and the first English historian who wrote these words (later translated by the poet Lord Byron), heard the news today, he might indeed believe that the end of the world was near.

According to Rome's authorities, the symbol of the Eternal City is in need of support as its south side is 16 inches lower than the north.

The leaning Colosseum might require the kind of structural intervention that straightened the Tower of Pisa.

"The concrete foundation on which the Colosseum rests is like a 42-foot-thick oval doughnut. There could be a stress fracture inside it," Giorgio Monti, from the department of structural engineering at Rome's La Sapienza University, told the Italian daily Corriere della Sera.

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The crack in the base below the 2,000-year-old arena may explain why the north and the south side of the monument are no longer horizontally aligned.

"If our doubts are confirmed, we are dealing with two structurally different monuments. At that point, it would be necessary to reunite them," Rossella Rea, the director of the Colosseum, said.

Rea has asked experts from Rome's Sapienza University and the Institute of Environmental Geology and Geoengineering (IGAG) to carry a scientific study on the phenomenon over the next year.

Marking one of the busiest intersections in the city, the Flavian Amphitheater (the Colosseum's proper name) is continuously rocked by vibrations from heavy traffic and a nearby underground metro.

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"Following the worrying news, we have begun collecting signatures to support the request for a vast pedestrian area in the streets surrounding the Colosseum and the Roman Forum," the environmental group Legambiente said in a statement.

According to Rea, the same sort of restoration work that saved the Leaning Tower of Pisa more than a decade ago might be needed.

Like the Tower of Pisa, which has been tilting since its construction in 1173, the Colosseum has been built on problematic soil.

The iconic symbol of imperial Rome was built in A.D. 72 by the Flavian emperor Vespasian on the marshy bed of a drained lake. It was opened in A.D. 80 by Vespasian's son Titus with a festival that lasted 100 days and included gladiatorial combats, fights with wild beasts and naval battles for which the arena was flooded.

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Over the centuries the Colosseum has survived three major earthquakes and disastrous fire. As the emperor Honorius prohibited the bloody gladiatorial combats in 404, the building fell into disuse and decay.

Medieval Romans used it as a garbage dump and a stone quarry for the construction of such buildings as Saint Peter's Basilica.

Today the monument receives over five million visitors a year.

A three-year restoration project will be presented tomorrow by the culture minister Lorenzo Ornaghi.

During the massive restoration, which should begin in December, the monument will remain open to tourists.