Wandering around a Paris craft shop one day in 1989, Shigeru Ban came across a Chinese bamboo hat.
Picking it up, the Japanese architect was intrigued by its design.
"I was amazed by the combination of the materials, the woven bamboo as a structure, the paper as waterproofing, and dried leaves underneath as insulation," he told AFP. "Just like the combination for a building's roof."
Twenty years on, the headwear stars in Ban's latest, most ambitious design: a new branch of France's top modern art museum, the Pompidou Centre.
It opens on Wednesday in the northern city of Metz, with a roof resembling a huge floppy Chinese hat.
"This is the biggest project I have ever done," said Ban, whose previous designs have included emergency shelters for refugees in countries including Rwanda and, recently, earthquake-ravaged Haiti.
"I have designed many other smaller buildings to study this kind of roof... but nobody has designed such a big timber roof," he told AFP at his office near the original Paris Pompidou Centre.
"It's the biggest Chinese hat ever."
The original Pompidou Centre draws in millions of visitors a year, sucking them up the glass tubes of its facade - a design by architects Renzo Piano and Richard Rogers seen as outlandish and caused a stir when it opened in 1977.
"The Pompidou Centre is a very special contemporary art museum and because of this famous building there was big pressure for me" in designing the new branch, Ban said.
His wooden roof sits above a ground floor facade of glass shutters that can open in warm weather to draw in visitors. In between lie three elevated shoebox-shaped galleries, the window of the top one framing a view of Metz.
"I wanted to find something contextual, instead of designing a building which can exist anywhere in the world. I wanted to connect the art museum to the city," Ban explained.
The Paris museum's novel appearance was intended to be "totally opposite... to the surrounding buildings," he explained. "I'm not saying which is better. But I think that my design is really appropriate for Metz."
The new museum has 5,000 square metres (107,000 square feet) of gallery space for rarely seen works by the likes of Henri Matisse, Pablo Picasso and Joan Miro.
The Pompidou has a vast collection of modern art but limited wall space at its Paris home obliges it to keep thousands of its treasures hidden. The Metz venue's eight-metre ceilings allow huge canvases such as Matisse's "The Sadness of the King" to be freed from storage.
The Pompidou joins other world-class museums such as the Louvre and the Guggenheim in looking to open its collections to new audiences by planting new branches elsewhere.
The so-called "antenna" museums aim to regenerate the surrounding regions as the Guggenheim did in Bilbao, an industrial city in northern Spain, which opened in 1997 with an avant-garde design by US-based architect Frank Gehry.
Metz hopes that its new museum will likewise boost the fortunes of a town traditionally known as an army base, which is set to see thousands of military jobs disappear due to restructuring.
"The Pompidou will radically change the image of Metz in France and in Europe," said the former mayor of the city, Jean-Marie Rausch, who helped launch the project. He forecasts the museum will get 400,000 visitors a year.
Meanwhile another northern French city, the former mining town of Lens, is preparing to receive its own outlet of world-class art when the Louvre - Paris's most visited museum - opens a sister branch there in 2012.
The Louvre Lens is also designed by Japanese architects - Kazuyo Sejima and Ryue Nishizawa of the Tokyo-based firm Sanaa.
They were not available for an interview but their plans foresee a series of rectangular buildings, contrasting strongly with Ban's hexagonal floating hat.
Ban refused to comment on the design for the other museum.
"I never take a look at the designs of others," he said. Neither did he discuss his own design with two acquaintances of his, the original Pompidou architects Piano and Rogers, he added. "An architect doesn't do that."Reuse content