Restoration of the carving will yield clues

It is thought to date back to the second or third century and will now be sent to Cardiff for specialist cleaning.

The conservation workers from the Welsh historic monuments body Cadw were removing the remains of a 19th Century farm building when the stone was uncovered.

It had apparently been re-used during the construction of the existing building.

The carving clearly shows a figure, possibly bearded, grasping a spear in his right hand and a shield in his left, advancing to the left.

God of war

He is thought to represent a Roman warrior, or perhaps Mars, the god of war.

Cadw said the find is one of the most exciting at Segontium since excavations were carried out there in the 1960s.

The carving will return to the museum at Segontium once the restoration work in Cardiff has been completed.

Segontium was a satellite fort of the main Roman settlement at Chester.

The fort has yielded an array of historic finds to piece together the Roman invasion of Wales, which was bitterly contested by the Celts until AD78.

North Wales was exploited by the Romans for its deposits of gold, silver and copper.