Archaeologists working deep beneath the entrance to Edinburgh Castle in Scotland have found part of a frontal artillery defence which was probably built around 350 years ago.

At an impenetrable two metres thick, it is thought the wall would have been constructed after damage caused by the sieges of 1640 and 1650 when the castle fell to the hands of the Covenanters and Oliver Cromwell respectively.

Peter Yeoman, Senior Archaeologist at Historic Scotland said: ”This discovery is very exciting as it just shows how much more history still remains beneath Edinburgh Castle.

“Before the first excavations in 1989, it was thought that the chance of anything archaeological surviving below the ground were slight, because the castle was built on a rock outcrop and had been redeveloped many times.

“Delightfully, we have been proven wrong again and again, and this new find will extend our knowledge of the Castle once more, adding another piece of history to Scotland’s iconic stronghold.”

Archaeological investigations have been continuing at the front area of the Castle as part of the ongoing project to create a new visitor reception area at Edinburgh Castle.

The £2.7m project began in September 2006 and will include a new ticket office and terrace, effectively halving the time taken to queue for tickets. It will also transform the visitors’ view of the Castle by removing the current ticket office from the esplanade.