By Emma Griffiths
BBC News, London
At 48m long and 3m tall (157 x 10ft), Poured Lines, due to be unveiled beneath a railway bridge near London's Tate Modern art gallery, is longer than five London buses and one of Britain's biggest outdoor paintings.
When abstract artist Ian Davenport agreed to create a huge painting at the gateway to London's Bankside, he had no idea what he was letting himself in for.
The idea was to create a local landmark at the entrance to the cultural district, home to the Tate Modern, the Globe theatre and National Film Theatre.
The noisy, previously pigeon-infested railway bridge might not have been every artist's idea of the best location to showcase their work.
But Turner Prize-nominated Mr Davenport liked the idea of the mural being on Southwark Street, used by more than 1m people a year, many of whom may never set foot in an art gallery.
He didn't realise it would take two years' work to create the massive piece which depicts painted lines, and which is hopefully sturdy enough to withstand grime, rain, vandals and pigeons.
"I've worked on large pieces before, I did a piece for Tate Britain a few years ago that was 17m long, but this was a bit of an epic," Mr Davenport, 40, said.
"It's a long time to work on one painting."
Just getting the necessary permissions from the various road, rail and local authorities took a while.
Strips of colour
Then there was six months of research to find the right material to make it sturdy enough to stand the test of time as a permanent outdoor fixture.
When Mr Davenport finally decided to use fluid enamel on steel panels, fired at 825 °C, he and his wife had to head to a remote factory in Germany, 50 miles from Dresden, to find somewhere with furnaces big enough to take the panels.
They stayed for three and a half months, setting up a studio in which to mix up the thin strips of 300 different colours.
Each were applied using special syringes to the 1m by 3m panels, which were then put in the furnace.
Three hundred colours were used in the piece
Once the work was complete, it was shipped back to England.
The pieces have since been hung "French door" style beneath the bridge, so they can be swung back when railway engineers need to carry out inspections.
It is part of wider efforts to regenerate Bankside, a well known cultural quarter.
The £290,000 bridge project has been largely funded by developers Land Securities, alongside Southwark Council.
The council hopes the work will draw people to the area for decades.
Councillor Richard Thomas said public art played a vital role in regenerating an area.
"The project...helps to reinforce the emergence of Bankside as the leading cultural quarter of London," he said.
Mr Davenport was keen to see people's reaction at the unveiling on Wednesday.
"It was a huge commitment, I had no idea it was going to take so long. I'm really looking forward to working with a smaller team for a bit."
The piece has been covered in vinyl for the past few weeks, but was briefly unveiled for some publicity photographs.
Some people went up to touch it, some liked it, at least one man shouted abuse from a passing car.
"That was quite amusing. It will have a lot of different reactions," said the abstract artist.
"The first thing the public sees is the colour, then hopefully over a period of time people walking past it everyday will be able to see subtleties and colour and textures."
Whether or not the enamel paint will resist the inevitable graffiti is yet to be seen - Southwark Council is nervous about calling it "vandal proof", for fear of attracting challengers.