Fresh excavations have started at a Roman town on the outskirts of Norwich, with archaeologists hoping to uncover more clues about the history of the site.

Archaeologists have spent the last two summers at the site of Venta Icenorum at Caistor St Edmund, with Channel 4's Time Team filming them for a TV special last year.

The archaeologists returned at the weekend for another three week of digging, this time excavating parts of the Roman forum.

Led by Dr Will Bowden, associate professor of Roman archaeology at the University of Nottingham, the team hope to find out when the forum was built and what happened to it in the later Roman period.

Parts of the site were originally excavated between 1929 and 1935 following the publication of dramatic aerial photographs showing evidence of streets and public buildings, which made national newspaper headlines.

Those who studied the site in 1929-35, thought the Roman forum had been destroyed by fire and lay in ruins for around a hundred years before it was rebuilt.

The team carrying out the new excavations are looking for evidence of that blaze and are also digging in the north west of the town.

They are looking for signs of what happened at Caistor after the Roman period and trying to find out whether the walled town was occupied during the Anglo-Saxon period, before it was eventually overshadowed by the rise of Norwich.

Dr Bowden said: 'It's going pretty well. It's early days yet, but we have opened up the trenches and we're now down into the archaeology now.

'Parts of the forum were dug before, but we're looking for the parts which have not been disturbed.'

He said the dig could end up rewriting the interpretation of the town, as it could demonstrate the Romans occupied it later than originally thought. He said: 'We have always thought of it as being about AD70, but its possibly AD120, which will put a different slant on the reason the town is here.'

The site is now a Scheduled Ancient Monument owned by the Norfolk Archaeological Trust and managed in partnership with South Norfolk Council.

The excavations are open to the public, free of charge, seven days a week until September 3. There will also be two family activity days where people can join in the dig.

Those events will run this Sunday (August 21) and the following Sunday (August 28).

You can follow the excavation blog at http://caistordig2011.wordpress.com or keep updated on Twitter by following @willbowden1 or #Caistor.