A stone circle believed to have been built 4,000 years ago has been vandalised.
Residents living near the Nine Ladies stone circle near Stanton Moor in the Peak District found the stones had been painted over the weekend.
The ancient monument dates back to the Bronze Age and is popular with walkers and pagan worshippers.
English Heritage said it was working with the local authority and police to investigate the damage.
Walkers spotted the stones had been painted yellow and green.
Anna Tattler, who lives nearby, said: "It is atrocious. It is a really special place and used for people to come and spend quiet, contemplative time here.
"It is a real shame the vandals have not recognised their importance and to deface them like that is pretty awful."
In 2000, environmental protesters had camped at the site in a long-running campaign against plans to reopen two dormant quarries near the monument.
Permission for the planning application was eventually revoked in 2008.
An English Heritage spokesman said the site may need specialist conservation work to remove the paint in order to avoid further damage.
He added: "Please don't try to remove the paint yourself as it could cause further damage."