Christo and Jeanne-Claude are well known for such large-scale work.

Claire Doole reports from Basle

Their most famous subjects have included the Reichstag building in Berlin and the Pont Neuf in Paris.

Now the husband-and-wife team have turned their attention to the natural world, with over 160 trees at the Berower Park in Basel all getting a new look this winter.

There's a tree in there somewhere

The idea is to hang a delicate material over the branches of the trees, creating a light and shadow effect as the the winter sun shines through the fabric.

Although less grandiose than earlier projects, Christo has clearly been enjoying directing the latest challenge.

"It was impossible to shape the forms in advance. That's the exciting thing about this project," he said.

"Each tree has its own personality."

The project involves 55,000 square metres (461,000 square feet) of woven polyester and 23 km (14 miles) of rope.

Striking effect: Looking through the fabric

Jean-Claude said: "There is a common denominator in most of our work that is the use of fabric."

This material lets air pass through, and is used in Japan to protect trees in winter, but Claude said the material has more than practical use.

"The cloth is the principle element to display the vulnerability, fragility and temporary character of our project.

Artist Jeanne-Claude: Each tree has its own sculpture

"It can be very opaque, very transparent, and very sensual. It is very fragile, You know that in a few days it will be gone.

"Of course that uniqueness creates a different kind of looking art"

Changes in light are spectacular

Weather permitting, the display will last a little longer - the trees are due to remain wrapped throughout Christmas until January.

The display coincides with a "Magic of Trees" exhibition inside the museum, which pays tribute to the way artists such as Picasso, Chagall, Cezanne and Giacometti have represented trees through the centuries.

Museum curator Marcus Brunderlin believes the work of Christo and Jeanne-Claude will stand the test of time.

"We will remember in a few years the wrapping of the Reichstag because it's a part of German history," he said.

A walk in the park with a difference

Up to 500,000 people are expected to come and see the trees, and the first visitors were impressed with the new covering for the skeletal winter trees.

"It's like summer again in the winter," said one. "That's fascinating."

But Jeanne-Claude warned people not to look too deeply.

"Our works of art are like all good art," she said.

"It is good for absolutely nothing else than being a work of art. It is not the symbol, it is not the message, it's only a work of art."