LONDON — The artist Christo on Monday unveiled 7,506 coloured barrels floating on a lake in central London, a puzzling installation designed to stimulate debate as much as the senses.

"The London Mastaba" on the Serpentine in Hyde Park, a trapezium-shaped work weighing 600 tonnes, was launched with an air of mystery by the Bulgarian-born US artist.

Twenty metres high, 30 metres wide and 40 metres long, some may see the metal barrels and wonder if there is an environmental message, thinking of barrels of oil in the heart of one of London’s green lungs.

Visible from several hundred metres away, others will see a prism, giant pixels, or a simple geometric creation.

However, the work is open to all interpretations and comes with no message attached, said its 83-year-old creator.

"There are no messages: there is something in it to discover yourself. I cannot direct you. You should develop your senses," he said.

Christo is known for his contemporary artworks including "The Pont Neuf Wrapped" (1985), which involved wrapping the oldest bridge in Paris in polyamide fabric, and "Wrapped Reichstag" (1995), a similar project on the parliament in Berlin.

"It’s created an enormous invitation, like a stairway to the sky," said the artist, on the banks of the lake popular with swans, ducks and tourists on pedalos.

Christo’s first major open-air art installation in Britain is in the shape of a mastaba, a type of ancient Egyptian tomb.

The floating platform is held in place with anchors.

Red with a white candy stripe on the sides, and blue, mauve and red on the ends, the barrels are a striking contrast with the lakeside surroundings.

"The colours will transform with the changes in the light and its reflection on the Serpentine lake will be like an abstract painting," said Christo.

’What in the world does it mean?’

The artist has long appreciated the low cost and aesthetic appeal of working with barrels.

In 1962, having fled Bulgaria, he blocked off a Paris street with a wall of them, in response to the Berlin Wall.

More recently, he created a wall of 13,000 barrels in Oberhausen in Germany.

Construction on "The London Mastaba", financed by the artist himself, started on April 3. It will stay in place until September 23, when it will be taken down and recycled.

The artwork is already drawing astonished reactions in Hyde Park.

"It’s very modern, but this place is nature and historical. I don’t like it here," said Turkish tourist Yasmin Koc Ozcengel, 46.

Another onlooker, Anna Andronova, said: "It’s good because if it was less brave in its shape and volume it would be less stunning."

Sheila Steffenson, 58, an American living in London, said: "I’m sitting here pondering what in the world does it mean... if it means anything.

"I’m just not really sure how I feel about it. Maybe it’s a message about pollution. Who knows?" — AFP