"The tombs could belong to a settlement and this would imply a new revision of the presumed date of the foundation of Rome," said Silvana Rizzi, director of the dig which found them.

"We should go back at least a century," she added.

Legend has held that Rome was founded in 753 BC by Romulus. He and his twin brother Remus were said to have been cast into the River Tiber as infants and washed up at the foot of the Palatine hill, where they were found and nursed by a she-wolf.

Roman historians believed that the twins, sons of the god Mars, promised to found a town where they had grown up and they returned to the Palatine in 753.

Caesar's rule

The tombs were uncovered in Caesar's Forum, not far from the ancient Coliseum in central Rome.

Archaeologists began the dig in that part of the forum just over a week ago. They found the round tombs complete with funerary urns.

Julius Caesar built his forum at lavish expense with money gained in the conquest of Gaul. The forum, adjacent to the old Imperial Forum, is closed to visitors.

Only about two-thirds of it has so far been uncovered - the rest lies beneath a main road called the Via dei Fori Imperiali.

Millennium fever

Silvana Rizzi said archaeologists had found the four tombs and a well in an area of the forum previously covered by asphalt.

"The find provides evidence that when Julius Caesar wanted to build his forum, he obliterated everything that was there before," she said.

Rome, which is an archaeological treasure-trove, has been transformed into a colossal building site to prepare for the Holy Year millennium celebrations.