THE world’s most iconic painting swapped the Louvre for the Brunel Shopping Centre this week, thanks to a world-renowned 3D artist.

At first glance, shoppers could be forgiven for thinking an underground vault had opened up to host the visit of Leonard Da Vinci’s masterpiece, the Mona Lisa.

But it was merely the latest work of talented pavement artist Julian Beever, who specialises in creating mind-boggling 3D optical illusions.

In five days, using only multi-coloured chalk and a grid, the pavement painter has painstakingly recreated Da Vinci’s iconic work as part of the Streetfest 2015 event in the town.

Julian’s expert techniques give the illusion that a chamber has opened up in the floor, with a painter perched precariously on the wall as he makes the finishing touches to the artwork.

But the painting has a twist, with Mona Lisa in turn painting the artist, to reflect this year’s theme of 'art'.

Julian said his mind started working as soon as he was given the event’s theme.

“This is art, within art, within art," he said. "This is probably the most famous artwork in the world and something that everyone can relate to. When I heard the theme was art I was instantly drawn to creating this.

“I’ve used Renaissance colours, murky greens, browns and reds which are evocative of the time. Then it is brought into the present day with the painter who in turn is being painted by Mona Lisa."

Julian must now battle back and knee ache as he spends up to eight hours each day crafting his own masterpiece.

Crowds have flocked to see the artist’s work which forms part of the Brunel Centre’s StreetFest 2015 festival, which features musicians, dance performances, craft workshops and a graffiti wall.

Old hand Julian, who is known for creating swimming pool, great white shark and giant snail illusions, said this represented an altogether new challenge for him.

“Part of it is trial and error," he explained.

"I sometimes struggle with visualisation so I will try things out. Luckily I can wash the chalk off if I need to."

And he said the most difficult part for him was constructing shadows to give the artwork its hidden depths.

“There’s also a difficulty creating the shadow of the painter so I’m going to try my best and hope it works," he said.

Julian’s 3D illusions are drawn in a special distortion which makes them appear to come to life when viewed from one particular viewpoint.

He will set up a camera so passing visitors can view the painting’s hidden depths.

“I have the vanishing point and drawing shadows and colour is integral to creating the illusion of depth,” he said.

In a 30-year career, Julian's stunning chalk drawings have drawn critical acclaim with his work popping up on streets from America to Asia.

Brunel Shopping Centre manager, Jane Stewart, said she was delighted with Julian’s efforts to create the artwork.

“Julian was the obvious choice for the festival," she said.

"His work is just incredible and he is so focused with what he does. The work is breathtaking and people walking past can’t believe what they're seeing."

The free Streetfest 2015 event gets underway from Friday and runs from 11am to 3.30pm, finishing on Sunday.