Archaeologists excavating the ground level of the bailey at the center of Lincoln Castle have uncovered a previously unknown tunnel connecting to a circular structure. The dig is in preparation for the future construction of a wheelchair-accessible elevator that would bring visitors up to the castle walls.

The find is exciting not just because it might well have been originally constructed as a secret passageway, which is inherently awesome, but because it’s the only medieval structure surviving inside the castle bailey. The newly-discovered structure has been provisionally dated to the 12th century, which makes it one of the first stone buildings in the castle.

Lincoln Castle was built by William the Conqueror just 2 years after the conquest to consolidate his power. In 1068 it was just a wooden keep, but it was later replaced by a stone one. The castle has been built on and over repeatedly since then, so finding original stone structures is a major coup.

County archaeologist Beryl Lott described it as an exciting and unique discovery.

She said: “There are no other known surviving remains of medieval structures within the castle bailey.

“These excavations have discovered the remains of a substantial stone building with a circular interior, possibly the remains of a stairwell or room below the current ground level of the castle bailey.

“The room is accessed by a doorway, which leads into a tunnel in the direction of the central bailey area.”

Lincoln Castle saw a lot of exciting action in the 12th century, most famously the battle between King Stephen and Empress Matilda in 1141. If you’ve read Ken Follett’s Pillars of the Earth, watched the sadly inferior TV series based thereon, or read the Cadfael book Dead Man’s Ransom, the First Battle of Lincoln featured prominently.

Stephen besieged Lincoln Castle where Matilda was holed up, but just when it looked like she was done for, her half-brother Robert of Gloucester charged in like the cavalry and won the day. Stephen was captured and Matilda garnered herself a short-lived spell — from February to June — on the throne of England. Who knows but Matilda might have taken cover in that passageway before her half-brother’s forces came to save her bacon.