Liverpool woke this morning to an unusual sight - a giant mechanical spider dangling down a high rise office building, the latest and strangest happening in the city's European Capital of Culture programme .

The three storey arachnid on the side of Concourse House was created by a French arts collective called La Machine, and promises to be the centrepiece of an enormous piece of street theatre.

When the beast - dubbed La Princess - wakes up on Friday morning, her legs will stretch out to nearly twice their length. Office workers had better beware because apparently she won't be in a good mood.

La Machine , led by artistic director Francois Delaroziere, has an impressive record. It was responsible for The Sultan's Elephant, a spectacular five-day programme in central London that began on May 4 2006 with a four metre wood and steel rocket crashlanding in Waterloo Place, embedding itself several feet into the road surface.

This was merely the start - it was followed by a mechanical elephant 12 metres high that roamed the city streets, the largest actor in a fairy tale drama based around the elephant's relationship with a small girl who had appeared to a Sultan in a dream.

La Machine's Liverpool show is alleged to be a lot edgier and less whimsical than The Sultan's Elephant , but no less jaw-dropping. The spectacle has been 18 months in the planning and surrounded by absolute secrecy, even though the show's protagonists have been rehearsing in the city for a month.

Helen Marriage, the co-director of British-based creative outfit Artichoke productions, which has been overseeing the project, said that the logistics had been formidable.

"In a theatre you'd use the set to rehearse, but we can't - we have to practise off-site and in secret," she said in a newspaper interview. "The first time we'll get on set is in front of the whole city; hence the 18-month planning period. You really can't over plan something this big.

"We've measured every road, removed street lights and even dug up a roundabout. Now we just have to hope it's all been accurate, otherwise, well, it could all turn into a bit of an excitement.'

In terms of popularity, the spider has a hard act to follow. The last thing to grace the side of Concourse House was a 100ft high photograph of Steven Gerrard.

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