Experts stunned to discover early Shakespearian theatre was rectangular

The Curtain Theatre – one of the three earliest purpose-built playhouses in England – was 30 metres long and 22 metres wide, and not round like as expected

Archaeologists undertaking the initial excavation work at The Curtain Theatre (AP)

Remarkable new archaeological discoveries in London are shedding fresh light on the birth of the English theatre.

Excavations of a 16th century Shakespearian playhouse in Shoreditch have revealed that, contrary to all expectations, the purpose-built theatre was rectangular – not polygonal or round like the Globe or the Swan.

"It's a total surprise to us," said one of the U.K.'s top Shakespeare scholars, Professor Stanley Wells, honorary president of the Shakespeare Birthplace Trust.

The rectangular shape reveals that the Curtain (and therefore potentially one or two other early theatres) were modelled on four-sided galleried inn courtyards – the major traditional venues for theatrical performances prior to the construction of the first purpose-built theatres.

Excavations, carried out by Museum of London Archaeology over the past week, have revealed that the Curtain Theatre – one of the three earliest purpose-built playhouses in England – was 30 metres long and 22 metres wide. The investigation has so far exposed the gravel surface of the open yard where the less wealthy members of the audience would have stood.

The brick footings of some of the theatre's outer walls have also been found – as have the inner walls which held the theatre’s galleries where better-off patrons would have sat. A substantial internal wall, immediately behind the stage, has also been discovered, as has part of the building's entranceway area – re-purposed from a previous structure on the site.

The discoveries have particular significance for understanding the staging of the premier of Shakespeare's Henry V. It has sometimes been suggested that Henry V was written to be performed at the Curtain Theatre – rather than at the Globe. But the newly discovered rectangular shape suggests that it is likely to have been performed at the Globe, not the Curtain – because in the opening verses of the play, its location is famously described as “this wooden O”.

But perhaps the most tantalising find unearthed by the archaeologists so far is a potential piece of Shakespearian era sound effect equipment – a late 16th century ceramic bird-song whistle. Although such objects were often used as children's toys in the Tudor and Stuart periods, the fact that this one was unearthed immediately outside the Curtain, suggests the possibility that it may have had some connection with the theatrical performances there.

Interestingly, just such a birdsong whistle may have been used during the performance of Romeo and Juliet at the Curtain in around 1598. Certainly such a whistle would have been appropriate for the famous scene in the play in which the two lovers argue as to whether a bird singing outside their window is a Nightingale (a bird which often sings during the night) or a lark – the herald of the dawn. It is a pivotal moment in the production. Juliet wants Romeo to stay and therefore interprets the birdsong as that of a Nightingale, while Romeo insists that it is a lark and that he must therefore leave immediately to escape being killed, as dawn is about to break.

The Curtain was one of the longest lasting theatres of 16th and17th century London and flourished from 1577 to sometime in the mid to late 1620s. Ben Johnson's Everyman in his Humour (featuring Shakespeare as an actor) was premiered there in 1598. William Rowley's Birth of Merlin was staged there in 1622, as was The Witch of Edmonton in 1621.

The excavation of the Curtain is being directed by archaeologist, Heather Knight. “This long awaited excavation is now starting give up the secrets of this historic site,” she said.

Archaeologists will continue to excavate the site for another month. The public can book tours to visit the site on Fridays from 20 May to 24 June. Tours are free but spaces are limited so booking is essential. Full details can be found at www.mola.org.uk/events.

Ultimately, the remains of this Shakespearian theatre will be permanently preserved in situ for visitors to admire alongside a permanent exhibition. What is likely to become a major London tourist attraction will form part of a £750 million 2.5 acre complex of retail facilities and office space – and 400 new high rise apartments. The complex – known as The Stage – is due to be completed by 2019.

“This mixed-use scheme is set to be a hub in East London, combining state-of-the-art offices, retail and residences with unique public amenities, while remembering the site’s underlying rich history,” said Jonathan Goldstein, Chief Executive of Cain Hoy Enterprises which is leading the consortium of investors, developing the site.