Experts at the country’s heritage body Historic Environment Scotland (HES) said the natural deterioration of ancient landmarks such as Edinburgh Castle and Orkney’s Skara Brae is being speeded up by the effects of climate change and will need extra care to be saved.
Properties in the care of the state represent six millennia of Scottish history and include many iconic sites of international importance.
Management of many of these as state assets extends back to the 14th century.
But the latest analysis has found more than half are now at serious risk from climate change.
Studies of 352 sites and monuments looked after by HES found that 89 per cent are exposed to “damaging” environmental effects.
Taking into account factors such as the presence of site staff and conservation teams, 53 per cent are thought to remain “at risk” from hazards such as flooding and erosion, with 28 judged to be at very high risk and 160 at high risk.
The HES report said climate change and extreme weather are putting “additional stresses” on historic buildings and “acting as a multiplier” to normal ageing.
Work to mitigate these effects has already begun at some sites, including rock containment at Edinburgh Castle and coastal protection works at Blackness Castle in West Lothian.
HES warned of “resource challenges” as it estimated investment of £65 million will be needed over the next decade to ensure the “satisfactory condition” of its properties, with an extra £2.1m needed each year thereafter to maintain that condition.
Culture secretary Fiona Hyslop, who commissioned the report, has confirmed Scottish Government funding of £6.6m will be provided to support conservation work, repairs and visitor facilities at sites including Doune, Stirling and Edinburgh castles.
She said: “These iconic buildings and monuments represent more than 6,000 years of Scottish history and include a number of internationally significant sites that attract thousands of visitors every year.
“By their nature, they are often difficult to care for and require specialist expertise to repair.
“Adding to this challenge, it is well understood that climate change is speeding up the natural process of decay at heritage sites across the world.
“HES’s new conservation study gives us a detailed understanding of the impact on our own heritage sites and tells us what is required to protect and preserve them for the future.”
Dr David Mitchell, HES director of conservation, said the report will provide a basis for investment decisions over the next decade and help determine how Scotland’s most cherished places and collections can be safeguarded.