The cairn at Western Beacon is among those which have been restored
Dozens of prehistoric sites on Dartmoor have been restored in a five-year project.
More than 30 Bronze Age cairns have now been taken off the English Heritage 'at risk' register as a result of the work.
Some 49 of the summit cairns, dating back to 2,000 BC, were surveyed and 31 needed restoration.
"These are scheduled ancient monuments so are very important," said Andy Crabb, archaeologist at Dartmoor National Park Authority (DNPA).
"They have the highest level of protection that we have in this country."
The project has just come to an end, but plans are under way to restore more of Dartmoor's 3,000 Bronze Age cairns - ancient burial mounds.
"We started with the cairns at the honey pot sites where they have been damaged," said Andy.
"We are on hold now until next year, when we will go back and assess some of the most exposed cairns."
The cairn at Butterdon Hill summit
The restoration work is being done by DNPA, English Heritage and volunteers from the Dartmoor Preservation Association.
Michael Nendick from the park authority said the work was vital: "Dartmoor is one of the most important places in western Europe when it comes to prehistoric sites - it was very highly populated.
"And the cairns are part of the cultural heritage of Dartmoor.
"So to have 31 of them removed from the 'at risk' register is fantastic, a real achievement."
One of the biggest risks to the cairns is disturbance from people visiting the sites.
"They just pick up the stones, not realising they are part of an ancient monument," said Michael.
During the survey work, the team learned more about how the cairns were constructed, and it is clear that they are not just random collections of stones.
"They are very complex," said Andy.
"They have multi-phases to them which were done over time and they were obviously carefully planned."
Previously unknown features within and around the cairns have also been identified, such as kerb stones, ring banks and smaller satellite cairns.
Andy said: "Not only is the project helping protect threatened archaeological sites on the moor, we have created a pool of highly skilled surveyors drawn from the local community who through their work are helping to increase our understanding of the past."