Alex Chinneck's spectacular levitating building in Covent Garden

Heads are turning in Covent Garden this morning, and they’re not just looking at the usual street performers – they’re gawping at a levitating building. Master of illusions Alex Chinneck’s latest mind-boggling public art installation is on show in what must surely be the spiritual home of his craft; one of the busiest piazzas in London and its theatrical hub. His floating building follows on from a sliding house, upside down house and many other puzzling optical illusions.

Called Take my lightning but don’t steal my thunder, Alex says: “The titles are born from a kind of daydreaming. Everything we do now is extremely planned and co-ordinated. And I don’t feel like an artist anymore. A title is a rare opportunity to do something which feels slightly bohemian!”

As for the thinking behind Take my lightning but don’t steal my thunder, Alex muses that “there are things which always come together but are always slightly apart.” In terms of the building itself, “the shape of the crack was reminiscent of the lightning bolt. It’s a very cataclysmic scene.”

About 50 people have been involved on this project, which has taken about eight months. Early this morning, paint-spattered construction workers were admiring the spectacle, leaning on the piazza’s marble pillars which Alex has replicated in his building. It’s been going up since Saturday, with the help of several 40ft trucks, a crane, three cherry-pickers and a veritable library of health and safety forms.

“It’s by far the most challenging project I’ve ever had,” Alex says. “We had to go through all the processes you’d go through building a full-size building.” The logistics are astronomical in relation to the concept. “The idea itself is actually quite simple. I don’t get too bogged down in concept or meaning or message. It is what it is. It’s playful and fun.”

For Alex, the problem-solving is part of the fun too. “It’s not so much about what, but about how. It’s when I realise how we’d create the illusion and how it would work visually that I become excited.”

The science behind this illusion follows the same principles of counterweight used by the levitating men – Alex says “through a kind of osmosis they got into my head” during the four days he spent in the piazza brewing his idea. In the green market stall to the side of the building there’s a 16-tonne steel beam which is attached to a steel platform and a 12-metre cantilever. The building itself is made from polystyrene glued to twin wool, which is usually employed in conservatory roofing. This polystyrene was digitally carved and then painted and distressed by a team of scenic artists.

Half the fun of the installation is in watching people’s reactions. One lady asked me if it was real, a bemused tourist went around the base rapping the pillars, commuters did double takes and then whipped out their smartphones, whilst a troop of school kids were the least confused of all. They just took the floating house in their crocodile-pair stride.

Alex says he doesn’t watch people’s reactions though. “It’s not a hobby, for the same reason that I don’t like reading the comments at the bottom of a blog. I’m not part of the work; I create them and then abandon them and I kind of like that.”

After so much hard work, does he ever think about quitting? “Over the weekend I was talking about stopping,” he admits. “But it’s an addiction; you can never really put it down. I’m addicted to these challenges.” Plus, he’s got “more titles than ideas at the moment.”

Alex Chinneck’s Take my lightning but don’t steal my thunder is on display until 24 October.