Banksy's theme part Dismaland has been revealed at a derelict seaside lido - featuring migrant boats, Jimmy Savile and an anarchist training camp.
The elusive artist has banned spray paint, marker pens, knives and "legal representatives of the Walt Disney Corporation" from the site in Weston-super-Mare, Somerset.
Residents had believed the 2.5-acre Tropicana site, a former lido, was being turned into a film shoot in a cover story maintained by the local council.
A sign reading "Dismaland" was erected across the front of the building and stewards wearing pink tabards with "Dismal" on the back began working there.
Visitors enter the theme park, which features work by dozens of artists, through a security check made from cardboard by Bill Barminski.
They are greeted with a view of the park and Banksy's fire-ravaged fairytale Cinderella Castle showing "how it feels to be a real princess".
There are boats full of asylum seekers which can be driven round a pond, two juggernauts performing ballet and a camp training guests how to break into bus billboards.
Banksy described the park as "a festival of art, amusements and entry-level anarchism", adding: "This is an art show for the 99% who'd rather be at Alton Towers."
The Bristol-based artist was inspired to create the park after peeking through a gap in the fence at the Tropicana site in January.
"It's not a swipe at Disney," he said. "I banned any imagery of Mickey Mouse from the site. It's a showcase for the best line-up of artists I could imagine, apart from the two who turned me down."
Banksy hand picked the artists featured in the show, who come from across the world including Israel, Palestine, Syria, the US and the UK.
He insists the site is not a "street art" show, adding that the art form is "just as reassuringly white, middle class and lacking in women as any other art movement".
Artists range from Jenny Holzer, the first woman to represent the US in the Venice Biennale, to Ed Hall, a pensioner who has spent 40 years producing trade union banners in his shed.
Artworks from Israel and Palestine hang side-by-side.
Much of the work requires audience participation, with visitors able to photograph themselves behind a seaside-style piece with cut-out faces, featuring pirates carrying rifles.
Inside Banksy's princess castle lies a dead Cinderella spilling out of her crashed carriage, lit up by a group of photographers flashing their cameras and the light of a motorbike.
A bus-mounted museum examines the role of design in social control, while a portable building in the children's area offers loans against their pocket money.
Julie Birchill has rewritten the Punch and Judy show, while a riot control vehicle commissioned to serve on the streets of Northern Ireland lies submerged in a swimming pool.
Stewards in matching tabards and Disney-style ears are also part of the exhibition and stare blankly at visitors as they go about their duties.
Asked about the meaning of Dismaland, Banksy replied: "I guess you'd say it's a theme park whose big theme is theme parks should have bigger themes."
Speaking at the site, artist Paco Pomet, from Spain, said: "It is really different to any other exhibitions I've seen before. It's really amazing. You can find really amazing pieces here, all of them have some kind of irony or wit.
"Most of the artists are talking about our world today, which is changing very quickly. We need to be aware of that. This kind of work is critical."
North Somerset Council leader Nigel Ashtonremained tight-lipped over when the authority had been made aware of Banksy's plans.
"It's a fantastic show," he said. "It's very, very thought provoking. Some of the messages are hard to accept but true nevertheless.
"We're extremely lucky that it's come here and I know there's a connection from the past when Banksy was in this area.
"Now is about the show but we hope that people will visit the show and then come to see the town and what north Somerset has to offer."
Only four people in the council were aware of the secret, he added.
Christopher Jobson, editor-in-chief of art blog Colossal, flew from Chicago and - without sleep - took two trains to arrive at Dismaland.
"It's absolute chaos," he said. "Of course, Banksy has a whole lot of artwork here, the entire premise is staffed with these kind of Dismal helpers that are shuffling you from place to place, there are fake games to play, and then there are legitimate artworks.
"There's an entire gallery of paintings and sculptures - there are at least 50 artists here from around the world and here is the middle of nowhere - he has done shows in New York, and even as close as Bristol, but this is a bit of a trek for a lot of people.
"It's so exciting that this is all here in this derelict old swimming pool. This is more of an experience than an art exhibit."
Dismaland will run twice a day from Saturday until September 27 and involve musical performances from Massive Attack, Pussy Riot and Kate Tempest.
A website set up for the theme park says: "Dismaland is situated on the seafront in legendary Weston-super-Mare and is easily accessible by train, bus and road."