Offa's Dyke Path

Hiking in Mid-Wales

The true purpose of Offa's Dyke, Britain's longest ancient monument, isn't known, although one theory is that the 2.4m-high earthwork was thrown up in the 8th century by the Anglian king, Offa, to defend his kingdom (Mercia) from Welsh Powys. Running for 176 miles across river valleys and through handsome market towns, it's best tackled in 12 stages.