135km from end to end, follows the course of northern Europe's largest surviving Roman monument, a 2nd-century fortification built - in the border country between England and Scotland - on the orders of the Emperor Hadrian in AD122. Opened in 2003, the path crosses the beautiful border country between England and Scotland. It is the first National Trail to follow the course of a UNESCO World Heritage Site. This week-long walk is regarded as one of the least challenging National Trails.