Heritage chiefs said they still have a lot to do at one of Scotland's top areas for landscape and wildlife.
The tenth birthday is being celebrated at Mar Lodge
The National Trust for Scotland has said tasks at the Mar Lodge estate near Braemar include repairing the entire 210km network of upland footpaths.
The trust is celebrating 10 years in charge of the estate, which is home to red squirrels and golden eagles.
The acres, in the heart of the Cairngorms National Park, lure more than 120,000 visitors per year.
Officials have stressed that since taking over the estate in 1995, they have restored mountain paths; significantly reduced the deer population in an effort regenerate trees and improved the moorland.
Deer numbers have been cut to 1,800 - but a row erupted earlier this year when helicopters were used to transport stalkers while they culled the animals.
Mar Lodge, dating back to the 19th Century, boasts four mountains, which are among the highest in Britain, and remnants of the ancient Caledonian pine forest.
Estate manager Alister Clunas said: "The wonderful thing is the regeneration of a whole landscape, but we've got to remember that it's over a long period. We're talking about a 200-year vision."
Dougie Baird, who is in charge of the estate's mountain paths, said that many had been quite badly damaged over the last 30 years or so.
He added: "We've established a 10-year programme to repair all those (paths) and get to the point where we can look after them just with maintenance.
"The work is technically very difficult and physically very demanding and requires a great deal of commitment from the people who carry it out."