A heritage expert has warned that increasing numbers of visitors to Hadrian's Wall may be damaging the historic site.
The wall stretches from Cumbria to Tyneside
Walkers have flocked to the Roman wall, which spans the north of England from Tyneside to Cumbria, many attracted by the 84-mile (135km) National Trail.
But Prof Peter Fowler, a United Nations World Heritage Advisor, said not enough was being done to protect the wall.
National Trails has argued it is doing all it can to prevent erosion.
Figures from the Countryside Agency show that in 2005, 65% more people walked the full length of the wall than in the previous year.
Prof Fowler said: "It's marvellous that more and more people are coming to visit Hadrian's Wall.
"My complaint is that not enough has been done in terms of the absolutely predictable consequences of more people walking the wall.
"The use of the wall for recreation purposes - challenge walking - is incompatible. It's a great pity that the trail was created. That creates problems. More people could have been encouraged to visit without creating the trail."
David McGlade, Hadrian's Wall path national trail officer, believes there has been a proper response to the threat of erosion.
He said: "The trail set up ten years ago a method of monitoring and surveying, and grassland management. The surveys show that the trail is doing fairly well in terms of condition, but we need to pay attention in other areas.
"I'm delighted that people come back to visit, but what we're trying to do is inform and educate people that there are simple things they can do to help us manage it."
He said wear to the path can be reduced by walking in single file.