Souvenir-hunters have chipped a lump off Stonehenge in the first case of vandalism at the world-renowned prehistoric site in Wiltshire for decades.
Two men attacked the 5,000-year-old ancient monument's Heel Stone with a hammer and screwdriver before being chased away.
The night-time vandals managed to hack off a small 10p-sized piece from the 16ft sarsen stone. The two men fled in a red Rover 400.
Taking "souvenirs" is now banned, although it was once allowed - with guides even handing out chisels to visitors.
A spokeswoman for English Heritage said: "Thanks to the vigilance and quick action of the security team at Stonehenge, very minimal damage was caused to the Heel Stone at Stonehenge.
"A tiny chip was taken from the north side of the Heel Stone with a screwdriver and hammer, but as soon as the two men were spotted by security guards they escaped over the fence and drove off. This is now a matter for the police."
Police believe the men could be the same two people caught on CCTV acting suspiciously a few days earlier.
A spokeswoman said: "Two male offenders were seen disturbing the monument with a hammer and screwdriver. A two-and-a-half-inch line was left on the stone. It is believed they could be two men seen acting suspiciously on a previous occasion.
"They left the site in a red Rover, with plastic sheeting covering the driver's side window."
Archaeologists are excavating the ancient site to discover more about its mysterious origins. The dig is the first to take place at Stonehenge for more than 40 years.