A 4,000-year-old stone circle in Orkney has been vandalised in a “mindless act”, Police Scotland have said.
Damage to the world-renowned Ring of Brodgar includes graffiti which has been engraved into one of the stones at the Neolithic site near Stenness.
It is believed to have been vandalised at some point last weekend.
Inspector David Hall said: “The stones at the Ring of Brodgar are priceless historical artefacts and the damage caused cannot simply be estimated in monetary terms.
“For someone to damage them in this way is a particularly mindless act.
“I would urge anyone who has visited the area over the last weekend to think back and if they believe they may have seen something suspicious, even if it didn’t seem of much note at the time, to let us know.”
The Ring of Brodgar originally consisted of 60 stones, with 36 surviving today.
It is within the Heart of Neolithic Orkney UNESCO World Heritage Site, which also includes a large chambered tomb called Maes Howe and the Stones of Stenness.
The ring was built between 2500 and 2000 BC and covers an area of almost 8,500 square metres.
It is the largest stone circle in Scotland and the third largest in the British Isles.
A Historic Environment Scotland spokeswoman said: “We were recently made aware of an incident of vandalism to the Ring of Brodgar.
“We would ask the public to be aware that causing reckless or deliberate damage to a scheduled monument is a criminal offence, and ask that anyone witnessing such acts report them to Police Scotland.”