Offa's Dyke evidence at Chirk suggests earlier build
8 April 2014 Last updated at 20:14 BST
Archaeologists have uncovered evidence which suggests that Offa's Dyke may have been built up to 200 years earlier than thought.
Samples from Clwyd-Powys Archaeological Trust excavations on a stretch of the dyke have been radiocarbon dated to the second half of the 6th Century.
Historians have always associated the dyke with King Offa who ruled the kingdom of Mercia in the 8th Century.
Roger Pinney reports.