A gang of thieves disguised as workmen tried to cash in on the popularity of guerilla artist Banksy - by trying to steal the door of a derelict building.
Banksy recently exhibited his work in Los Angeles
The Bristol-based artist had daubed a painting on the steel door in Slater Street, Liverpool, as part of the city's biennial in 2004.
The gang attempted to steal it but they were scared off by cleaners.
Work by Banksy is soaring in value, and at a recent auction one of his spray paintings sold for £62,400.
Hollywood actress Angelina Jolie reportedly spent more than £200,000 on work by Banksy at a recent Los Angeles sale.
The work on the door, known as Liverpool Love Rat, has not been valued but is now under lock and key.
Jane Mills, director of Jacaranda Developments which owns the building, said: "These men just turned up dressed like builders and carrying tools.
"They tried to get the door off but it is very heavy and I think they were struggling.
"One of our cleaners spotted them and asked them what they were doing and they just ran off.
"It's a shame but we've had to move the door from public view and to a secret location because of this."
Ms Mills said she was now deciding what to do with the artwork following the attempted theft in October.
Banksy's last sale - a painting used on the cover of Blur's Think Tank album - went for 10 times its estimated value at Bonhams.
Another piece of his art produced for the same album, called Young Child With Bird, was sold for £31,200 - more than four times its estimate.
And at a Sotheby's sale in the previous week, his six silk-screen prints of model Kate Moss in the style of Andy Warhol's Marilyn Monroe pictures were auctioned for more than £50,000.
The artist has become notorious for his public stunts, including tampering with copies of Paris Hilton's album, showing the singer topless and with a dog's head.
An exhibition in Los Angeles, called Barely Legal, provoked criticism for his use of a live painted elephant.
In 2005, he targeted a security wall in Israel, creating nine stencil sprays on the Palestinian side of the West Bank barrier.