Part of a massive wall started in around 600 BC around the central Italian town of Amelia collapsed on Wednesday morning for reasons still unclear .

The so-called Polygonal walls around Amelia are famous not only for their age but also their size. Built out of huge polygonal stones, they are 8-10 metres high and about 3.5 metres thick .

The 20-metre section of wall which collapsed was undergoing restoration work in recent weeks although activity had been suspended for a few days because of bad weather .

Central Italy recorded record rainfall in December, a fact which experts are taking into account as they study the broken section .

Police and fire services confirmed that no one had been hurt by the collapse. Scaffolding set up for restoration was destroyed and a car parked nearby was slightly damaged .

Located some 55 miles north of Rome in Umbria, Amelia was in ancient times called Ameria. The city was said by Latin author Pliny to have been founded at least three centuries before Rome .

Archaeological experts were expected to examine the rubble on Wednesday in efforts to see whether the collapsed section of wall could be rebuilt .

The 800-metre long wall, which now has a breach in the section to the right of the old city gate, has always impressed archaeologists for the skill with which it was built .

According to local legend, it was constructed by the Cyclops, the one-eyed monster encountered by Greek hero Ulysses .

Amelia was founded by Umbri king Amero who gave it his name .