The remains of a painting of a horse and rider are on fire on the outskirts of the ancient city of Ephesus, near the Mediterranean coast.
The painting is one of three that date back to the 2nd millennium BC.
Experts have estimated the painting is around 50,000 years old, but it is now believed to be in an open state.
They believe it was made by an ancient artisans using a paint marker.
It is now being cleaned by hand, the owners of the painting told the AP news agency on Wednesday.
A spokeswoman for the Ephesian Antiquities Ministry told the Reuters news agency that the painting had been left to dry, adding that the owner had requested permission to move it to a museum.
The city of Gnaion has an ancient history dating back to around 2,000 BC, and it has been under the control of the Roman Empire since the 4th century BC.
The Ephesians had to fight off the invading Romans, who also used the city to manufacture pottery and other items, including pottery with gold.
The area has been covered by graffiti since the Roman period, and some have used the ancient art as a reminder of their struggles to survive in a hostile environment.