A youth club hopes to raise £100,000 by selling a Banksy artwork it removed from a wall with a crowbar.
A picture of Mobile Lovers was posted on the celebrated street artist's website yesterday but its whereabouts were not disclosed.
However, the location was identified today as Clement Street, within sight of the city's bustling shopping centre.
Fans travelled to the street to admire the image, which was painted on a black piece of wood screwed on to a wall.
But at 4pm, a group of men from the financially struggling Broad Plain & Riverside Youth Project - situated just beside the piece - used crowbars to remove it.
Dennis Stinchcombe, 58, leader of the youth project, said the piece would be sold to raise funds to keep the centre open.
"I was approached by somebody who knows Banksy very well," Mr Stinchcombe said.
"He's an artist himself and he said, 'you need to take that Dennis, get it into that club - it's what it is meant for'.
"Banksy never does his street art on pieces of wood - they are always on walls so they can't be taken away.
"We need £120,000 to keep going and our fundraising appeal has so far only brought a few thousand pounds.
"Now we've ended up with a Banksy on our doorstep. It is a dream come true. I'm absolutely buzzing."
By 6pm, planks of wood had been screwed over the empty doorway, with a notice urging fans to visit the piece at the club by paying a donation.
Mr Stinchcombe said Mobile Lovers had been placed as close as possible to the club, which is behind tall locked gates.
"He has done it to help the right people," he said. "Somebody was saying it is worth £40,000 but I am hoping for £100,000.
"We will let people come and see it here for a while, then get it to Bonhams for valuation."
The club, which is attended by 1,000 young people every month, has been operating for 120 years.
Mr Stinchcombe, who has been working at the club for 40 years, initially spotted the piece at 9.15am on Monday.
He did not believe it was an authentic Banksy until later that evening, when a friend spotted it on the street artist's website.
After realising the worth of the piece, Mr Stinchcombe guarded it until receiving the tip-off that he should remove it.
"If we hadn't taken it, someone would have ripped it from the wall or vandalised it," he added.
The discovery of Mobile Lovers comes days after a piece depicting three 1950s-style agents listening in on conversations in a telephone box appeared on a house in Cheltenham.
Mobile Lovers looked out on the A4032, the busy main road leading into Bristol from the M32.
Art fans from around the city and beyond flocked to see the piece after work but were disappointed to find it had already been removed.
Rachel Dean, a puzzles compiler who cycled to see the artwork, said: "It's a real shame because it ruins it. The whole point of street art is that it's there."
Laura Pique, 21, a fine arts student at UWE Bristol, said: "If it was my door I wouldn't be happy that it had been taken. Street art is on the streets, you shouldn't have to pay for it."
David Bryant, 54, of Bristol, was horrified after seeing black painted boards in place of the Banksy.
"I came all the way down here and I find it's gone and someone is making money out of it. That's not what Banksy is about, he is not about money.
"What is odd is that it was on a piece of wood. Banksy never puts street art on anything that can be taken away."
Bristol City Council said it could not be "100% certain" of the ownership of the wall the piece had been screwed on to.