Archaeologists have unearthed a fascinating find dating back to the 14th century while excavating at Rochester Castle.

An archway leading to a small chamber with a large shaft above, known as a water gate, has been discovered alongside the wall on the Esplanade.

The fortified gate was probably used to transport goods from the riverside to the castle, according to the Rochester Bridge Trust, which commissioned the dig.

In medieval times it would have also been used to allow those within the fort direct access to water transport.

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: “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 water gate 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 now 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, said: “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.