A fascinating 14th century chamber discovered during excavation work on a medieval castle is to open for virtual exhibit.

Rochester's Bridge Chapel is set to re-open to the public next month - and will feature a virtual fly-through of a fortified gate which was unearthed by archaeologists at Rochester Castle.

The archway, leading to a small room and large shaft above, is known as a watergate as it was probably used to transport goods from the riverside.

That's the theory of the Rochester Bridge Trust, which owns one of the few surviving bridge chapels in the country, and commissioned the dig alongside the wall on the Esplanade in 2018.

In the Middle Ages, it would have been used to allow those within the castle get direct access to water transport.

Alison Cable, the trust's archives and records manager, said: "The watergate was found during preliminary groundwork ahead of the Rochester Bridge refurbishment project.

"At the time it was photographed and scanned to enable a 3D visualisation to be created before the entrance was sealed for public safety.

"The scans enable ongoing study of this unusual feature that's hidden beneath our feet, and now we are pleased to be able to share this visualisation with our visitors, so they can have a greater understanding of the history of Rochester Esplanade."

The watergate can be seen in the court room of the Victorian Bridge Chamber where the court of wardens and assistants hold their committee meetings.

Visitors will also be able to see a selection of artefacts discovered in or around Rochester's bridges, historic art and furniture and the medieval bridge chapel which was constructed more than 600 years ago.

Experts said the materials used to construct the entrance arch were of particular interest.

While Kentish ragstone was used, there was also evidence of tufa which has not been quarried since 1150.

There was also peg-tile which was used in Rochester around 1200 and a yellow brick from around 1375.

Roy Porter, an English Heritage curator, said following the discovery: "This work has offered an exciting opportunity to reveal a long-hidden part of the castle.

"It has given us the chance to explore the significance of the watergate and, along with colleagues from Historic England, to make a record of the details to help further our understanding of the castle’s rich history.

"It is a wonderful reminder of quite how many layers of history our castles and historic buildings contain, and for the people of Rochester, going about their daily life.

“I’d say pause for a moment and wonder, just what might be beneath your feet?”

The hole in the front of the gate has been closed and the footway rebuilt.

But the information gathered during the investigation and the scans that were carried out mean it will continue to be studied for some time to come.

Peter Kendall, of Historic England, added: “Laser scanning and data processing can be a great help in understanding the past, especially in such inaccessible places as this where the water gate is buried underground.

"It means we are still able to study the structure even though access to it has now been sealed."

Designed to command an important river crossing, the castle was built in stone by Gundulf, Bishop of Rochester, in the 1080s.

It endured three sieges, including a famous assault by King John in 1215, when one corner of the keep was destroyed.

It became redundant as a royal stronghold in the late Middle Ages and fell into ruin in the 17th century, but remains a potent symbol of medieval secular power.

The buildings are fully accessible and entry is free with no booking required.

Doors are open from 11am to 4pm on Thursdays and Saturdays from Thursday February 2.