What could back gardens on the Shropshire/Mid Wales border soon have in common with the Great Barrier Reef and the Taj Mahal? Answer – they could soon become Unesco World Heritage Sites.

It sounds strange, but Offa’s Dyke, which runs through several gardens, has now been nominated for the World Heritage Status, along with the likes of Blackpool and the Forth Bridge in Scotland.

The move follows a call from the Department for Culture, Media and Sport for nominations to join the ranks of the Taj Mahal and Shropshire’s Ironbridge Gorge.

A total of 38 nominations came forward, hoping to be included on the tentative list of sites, including Offa’s Dyke.

If approved it would be the first World Heritage Site to directly affect Powys, as large parts of Offa’s Dyke go through the county and the Offa’s Dyke Centre is based in Knighton.

The Offa’s Dyke will face competition from the Wye Valley and the Forest of Dean, Merthyr Tydfil and the Slate Industry of North Wales, which are all hoping to be listed.

It is one of 38 sites in Great Britain that are looking to be listed, which also includes Brunel’s Great Western Railway.

Dating from the eighth century, Offa’s Dyke is a great frontier earthwork built by Offa, King of Mercia.

It gives its name to a long distance footpath, one of Britain’s National Trails, which runs from Chepstow to Prestatyn through the varied landscapes of the Welsh Marches.

In places, it is up to 65 feet wide and eight feet high and in some areas even goes through gardens.

The origins of the Dyke are so shrouded in mystery that many of its aspects are speculated upon rather than being fully understood.

Chris Martin, from Clwyd-Powys Archaeological Trust, regional archaeologist for almost all of the Welsh section of Offa’s Dyke, said: “Along its length the Dyke has so many different ownerships — some parts even go through people’s back gardens.

“However we support the bid all the way, it’s a bold and ambitious task, and we would encourage people to look at it sensibly.”

By Andrew Morris