A secret passageway has been found beneath the stage of the theater where William Shakespeare's Henry V, and possibly Romeo and Juliet, were first performed.

The unusual feature was found at the site of the Curtain Theater, one of London's earliest playhouses. Excavations showed the stage of the 16th-century building was much longer than originally thought, and contained evidence of a mysterious passageway running beneath it.

"The passage would allow actors to pass unseen from one side of the stage to the other. This raises lots of questions as to how early plays were staged," Heather Knight, senior archaeologist at the Museum of London Archaeology (MOLA), told Seeker.

Re-discovered in 2011 behind a pub in Shoreditch, east London, the Curtain - named after the road it fronted - opened in 1577. It was only a few hundred yards from London's first playhouse, The Theater, which had opened a year before, in 1576.

The theater is closely connected with Shakespeare. It was home to his Company, the Lord Chamberlain's Men, from 1597 until another playhouse, The Globe, opened two years later.

RELATED: Big Data Reveals Shakespeare Had a Co-Author

Despite being immortalized as "this wooden O" in Henry V, the Curtain was intentionally built as a rectangular playhouse.

"This was not a re-purposed space with a stage, it was a place where people came to be immersed in entertainment," MOLA said in a statement.

Moreover the stage, measuring nearly 46 feet long and just under 16 feet wide, had a shape unlike any other Elizabethan theaters.

The finding raises questions about the function of the theater and the types of entertainment that might have been staged there.

"Did the unusual shape and layout of the Curtain stage influence the plays such as Henry V and Romeo and Juliet that he wrote before his company moved to the Globe with a different stage? As well as drama, could the Curtain's stage space have been used for sporting spectacles?" Knight wondered.

She added that more in-depth analysis of the finds will follow to shed some light on some of those mysteries.

RELATED: Oysters and Crabs, the Popcorn of Shakespearean Theatergoers

Meanwhile, the researchers learned that the Curtain was one of the earliest Elizabethan playhouses where people paid money to see performances.

It had timber galleries with mid and upper areas for those who could afford to spend more and a courtyard made from compacted gravel for those with less to spend.

Knight's team found fragments of ceramic money boxes which would have been used to collect the entry fees from theatergoers. The boxes were then smashed and the released money counted in a separate room that was called the 'box office' - the term we still use today.

Finds include glass beads and pins, which most likely come from actors' costumes. Drinking vessels and clay pipes were also found throughout the theater and likely belonged to reveling theatergoers and actors.

The Curtain's foundations will remain on permanent display alongside the unearthed finds as part of a visitor center at the heart of a major redevelopment called The Stage, which will include shops, restaurants and more than 400 homes.