London Museum's Taryn Nixon explains the significance of the find
Archaeologists believe they have unearthed the remains of Shakespeare's first theatre, the BBC has learned.
A team from the Museum of London found the remains of the theatre in Shoreditch last summer.
Built in 1576, it is thought the Bard acted there and that it also hosted the premiere of Romeo and Juliet.
Meanwhile, a portrait of Shakespeare, thought to be the only surviving image of him made during his lifetime, has been unveiled in London.
Taryn Nixon, from the Museum of London, said her team had found part of the original curved wall of the playhouse, which was believed to be polygonal in shape.
A metre and a half below street level, it has also uncovered the gravel surface, gently sloping down towards the stage, where the bulk of the audience would have stood.
But the archaeologists fear the stage itself may be buried underneath a housing development.
Ms Nixon told the BBC the theatre was built in what were known as "the suburbs of sin" just outside the city.
"The Lord Mayor actually passed a decree that there shouldn't be any theatrical performances in the city... so just on the edge of the city is actually, classically, where you find all the slightly wilder, slightly more fun activities going on," she said.
Finds made within the gravel yard include a fragment of 16th-century pottery featuring the image of a man with beard and ruff.
The theatre was constructed by James Burbage, possibly using bricks from an old priory.
It is thought to have played host to Shakespeare's theatre company, the Chamberlain's Men.
About 25 years after it was built, it was dismantled and moved timber by timber to construct the Globe Theatre on the South Bank of the Thames.
In the 1990s the Globe was recreated on a site nearby.
Penny Tuerk, from the Tower Theatre Company, said Romeo and Juliet and an early version of Hamlet were thought to have been performed at the excavated site, as were some of Shakespeare's comedies, like A Midsummer Night's Dream.
"There was a huge appetite for theatre at the time," she said.
"People were flocking into the theatres and they would have grabbed anything that they could and put it on to please the crowds."
The site is now owned by the Tower Theatre Company. It plans to preserve the architecture in situ and construct a new playhouse around it which will open in 2012.
The painting of Shakespeare is thought to date from 1610
Ms Tuerk said it would be a 21st Century equivalent of the original playhouse - a "no frills, hard-working place of entertainment" - that would bring London theatre "back to its roots".
"Imagine actors in the future crossing the theatre and perhaps paying homage to Shakespeare as they go on stage for luck," she added.
Elsewhere on Monday, Professor Stanley Wells, chairman of The Shakespeare Birthplace Trust, unveiled a newly identified portrait of the Bard.
The picture is owned by art restorer Alec Cobbe and is believed to have been painted in 1610, six years before the playwright's death at the age of 52.
There has long been controversy over the accuracy of some representations of him and many have been discredited in recent years.
Most experts generally agree that the most accurate posthumously made depictions are a bust in Holy Trinity Church in Stratford-upon-Avon and an engraving made for the title page of the first collected edition of his work.
The portrait will go on display to the public in Stratford-upon-Avon on 23 April, Shakespeare's birthday.
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