An archaeologist has warned in a report that urgent action is needed to protect the trail along Hadrian's Wall from further serious erosion.
The trail was opened in 2003.
About 400,000 people have visited parts of the trail, which runs from Cumbria to Tyneside, in the last two years.
Former Newcastle University head of archaeology Prof Peter Fowler said he was "alarmed" at the trail's state.
The organisations responsible for the site said they have systems in place to monitor and manage the trail.
Prof Fowler said: "I was really quite alarmed. The problem is that the trail is very close to the wall and it doesn't seem in any significant way to be being managed.
"It's not the walkers, it's the lack of management of the walkers and the lack of management of the trail which is causing the erosion and the wearing of the path which in places is 10 to 15cm deep."
World Heritage Site Management Plan Committee chairman Dr Peter Stone said the trail would not be closed to the public but it was time to look at the situation very carefully
He said there was a high level of monitoring of the site and organisations involved were looking at the situation.
He said: "The issue is that there is an amount of erosion going on, differing erosion in differing places and we have to make sure those places where the erosion is taking place are monitored and the erosion is dealt with by the Countryside Agency."
In a statement, the Countryside Agency said it took protecting the wall very seriously and there were "robust" systems in place to monitor and manage the trail.
It said there were more than 700 owners of the wall.
The statement added: "The Countryside Agency has been monitoring the Hadrian's wall path National Trail on an ongoing basis since it opened in May 2003 and is already aware of the issues at the sites noted. Steps are being taken, or planned, to address the issues."