Naked flames will light up the dark historic space in the form of four-metre wide fireballs, a furnace wheel billowing smoke and flames, walls of flaming pots, and a huge burning chandelier, all to the sound live music in the City Chambers Quadrangle drifting in from Parliament Square.

Given that it promises to be pretty jaw-dropping, it may come as a surprise that the fiery spectacle – the first in Scotland by the internationally-renowned French street art company Carabosse – will have no name. “No, it has no title as such,” says Carabosse’s artistic director Gerard Court. “Remember, this is not a performance, it’s an installation. We create a universe with light, heat and music in public places. People will be drawn to it and will take from it different things. So we just call it an Installation of Fire.”

Don’t be fooled by his Gallic nonchalance, though. When it comes to discussing the magnetic draw of the naked flame, his enthusiasm is catching.

“Flames create a magical atmosphere and are really quite staggering. They somehow engage people instantly,” he begins. “They evoke images that we absorb, and they open up human emotions and unleash poetry, the unspoken.” Why does he think we react so to this most dangerous of all the elements? “It must be a primeval thing, because in contemporary life we are less and less involved with fire than were previous generations, yet we smile and gasp when we see the fires, as if in recognition,” he says, a little breathlessly. “People are drawn to fire. It’s like a return to innocence, and it’s a universal reaction. But they do not try to reach out and touch it. Some even cry. When we were up in the Austrian mountains, an old man came walking up to us, and was overwhelmed with tears. He was completely caught off guard. That’s the difference between an installation and a performance.”

In addition to the effect on humans, flames also have the power to transform a place from disused or unattractive to beautiful and even magical. “Each place is different, even though it’s the same fire. With our installations, we try not to spoil the beautiful, but to erase the ugly. Edinburgh, of course, is always magical and atmospheric, so although every piece we do is already unique, we are trying to do something a little bit more,” says Court.

To this end, 10 mechanical robots will walk up and down among the flames, casting huge man-shaped shadows onto the wall of St Giles’ Cathedral, that dramatic icon of the Scottish Reformation – which next year marks its 450th anniversary. Carabosse’s robots aren’t necessarily intended to represent anyone as specific as Knox or Calvin, but it’s a lighthearted way of drawing attention to those uniquely Scottish characters. Court’s interest lies more in creating an atmosphere that is medieval in essence and which will “light up the eyes and open the spirit”.

“This is about getting people together and inspriing them.”

He means the dead as well as the living. For inside St Giles’ itself, Carabosse will also have a presence. In what can safely be described as a first for the High Kirk, hundreds of Carabosse vests will be strung on wires across the vaulted space, and lit by burning candles, to signify the spirits of the departed.

Their anarchic willingness to make art where others dare not is what makes Carabosse different from other French street performers known to Edinburgh audiences, such as Le Cirque du Soleil, Archaos, Opposito and Transe Express, says Edinburgh’s Hogmanay director Peter Irvine. “Carabosse is less about performance and more about the creation of art pieces. They have ability to take a single simple idea and execute it beautifully. I’m sure Calvin and Knox would have said this is what not to do.”

Court’s idea is to create a backdrop for the robotic performance by attaching hundreds of fire pots to the walls of Parliament Square, all at different levels, although at the time of writing Carabosse was still in negotiation with the listed building’s owners Edinburgh Sheriff Court about that. Court says: “We have worked in other historic cities before with absolutely no risk, but Edinburgh is being more particular.” If permission is granted to use the space, spectators would be able to walk over Parking Bay 46 – the site, reveals a gleeful Irvine, of Knox’s grave, in which he would be turning at the very thought.

Previous venues for Carabosse’s works include the foot of the Kremlin in Moscow, the oasis town of Essakane in the Malian desert north of Timbuktu, Albania and Adelaïde. The company’s most recent visit to the UK was last September, when they brought Fire Garden to the forecourt of Tate Modern and at Hull’s Freedom Festival. Peter Irvine saw Carabosse in Barcelona in 2008 and was so moved by what he describes as their “beauty and simplicity” that he invited them to Edinburgh for their Scottish debut .

So, on December 26, some 2500 specially-made terracotta pots arrived in Edinburgh from the tiny village of St-Christophe-sur-roc in the Deux Sevres region of western France, where the company has its HQ in a converted dairy. Thirteen members of the Carabosse company are now constructing the various cast iron frames, attaching the pots – turned by a local Franch artisan – to construct the breathtaking centrepiece of the installation: an elaborate, eight-metre-high metal lustre chandelier that weighs more than a tonne and will be lit up by hundreds of naked flames. The specially-composed music will be computer-generated guitar and harmonica.

Interestingly, Court says that adding colour to the flames doesn’t really work. First, the materials involved are too expensive. “Secondly, we have found that the light from coloured flames doesn’t travel as well as the light of natural ones.”

Such are the vagaries of street art in Scotland that it will always be subject to the mood of Mother McNature. What if – whisper it – the weather turns wet on the night? Again, Court is sanguine.

“If the fires are already lit, a little bit of rain won’t harm them. But if it starts to rain before they’re lit, or if it becomes really heavy at any point, then that is a problem,” he says. “But all going well, it will b a bit of fun and it should be a very pleasant experience for all.”

Elemental, mon petit feu.

Carabosse’s free outdoor Fire Installation on the Royal Mile will be alight from 7pm-11pm on Wednesday December 30 and from 4pm-8pm on January 1, 2010.