Architecture: At home with the space generation

Gehry has pushed back the frontiers of design. How apt that his work should be celebrated in another great innovator's house.

THE AMERICAN architect Frank Gehry's Guggenheim museum in Bilbao, Spain is the most celebrated new building this century, so popular that "doing the Gu" has triggered weekend breaks to Bilbao from all over the world. More than just a pretty face, the beautiful building, clad in titanium and rising from industrial ruins, has brought new life to a once-overlooked, post-industrial Spanish city.

A brilliant new exhibition to explain Frank Gehry's method of working opens this week at the Soane Museum in London's Lincoln's Inn Fields, showing how he gives his buildings this dynamic centrifugal force.

The curator, the Danish architect Kirsten Kiser, persuaded a reluctant Gehry to ship over sketches that seem to spin off the page, the models that he endlessly tweaks over a building's evolution, cladding samples, and photographic collages of many different buildings. It is set up as though the architect had just left the studio for five minutes.

This is the first time that an exhibition has been shown in the drawing- room at Soane's museum, - "the most magical building in London", as the architecture critic Charles Jencks describes it. "Gehry and Soane share a quixotic brilliance, a sense of delight and a Spartan aestheticism. It's absolutely right that Frank is there."

Sir John Soane (1753-1837) lived in this tall, narrow, terraced house from 1813 until his death, and so strongly did he leave his mark that there is a mysterious sense of his presence lingering in the classical drawing-room. A hundred years after his death, Sir John Betjeman wrote in the visitor's book: "He must have popped out - sorry I missed him."

At first sight it seems as though a car boot sale has opened in the citric- yellow drawing-room of Sir John Soane's house. Dynamic sketches by Gehry of what appear to be monsters arising from pools - fluid, not at all like a building as we know it, but full of energy and promise - are propped casually against the wall.

Amid all the Georgian furniture, Frank's Big Easy chair, which is a complicated mesh of bentwood seamlessly woven so that there are no joints between backs, seat and legs, is pulled up to the table. So are his cardboard chairs with chewed edges, made for the Vitra Design Museum in Basel. On the table with his sketches are the only explanation of the exhibition, in the form of photocopies of newspaper articles on the great man and his latest works. It is a bold presentation.

Building-blocks pinned to tracing paper show the way in which Gehry plans the mass and volume that buildings occupy on site. He always begins with children's blocks, harking back to childhood games on his grandmother's veranda in Toronto. Now the game is serious, yet the architect dissembles to make it look playful. He divides these blocks and splits them, then swivels and skews them as he sorts out their relationship to each other.

"He always changes the scale of his models, making them much smaller or enlarging them as he reworks the project, so that they never become an object," says Kirsten Kiser. "They're not sculptural, but endlessly refined working models." Raw models of his buildings seem to be cut from loo rolls. Sometimes they have silver or mesh or Perspex pieces added to them, to spill over the sides or spew from the roof in waves of such fluidity that he puts a brain surgeon's probe inside the final models to explore in detail the curvature on screen.

Three big, shapely pieces stand on the 18th-century console table. "The three Buddhas," as Gehry graphically describes them, fit neatly over the campus at Weatherhead School of Management in Cleveland to house free- standing lecture halls in stacks, with light beamed in from the roof. Some of the residents were dismayed when they saw the onion domes spilling out of a brick base; Frank Gehry hasn't always been feted. Like Soane, who was never accepted by the establishment in his lifetime, Frank Gehry was out in the cold for a long time.

A pair of riding-boot shoehorns cast in plaster turn out to be Fred and Ginger, as he calls the pair of towers built in Prague. The Nationale Nederlanden building is one of only three new buildings in Baroque central Prague. As the building turns the corner, opaque Fred, coupled with transparent glass Ginger, twirls on shapely legs.

The pair were cast in plaster, digitised and refined in virtual models. Then they were churned out again in physical form with the help of a three- axis, computer-controlled milling-machine and given to the contractors to help them get the accurate measurements for the building's irrational geometry.

Deep purple metallic sheets, vibrant against red and blue ones, lean against the yellow wall. This turns out to be the Experience Music Project at Seattle, which is a 110,000-square-foot faculty to celebrate American pop music. Buildings inspired in part by a shattered Fender Stratocaster electric guitar cluster around the purple Sky Church homage to Jimi Hendrix.

The longer you spend here looking at Gehry, the more you will discover about Soane. Long before electricity, this 18th-century architect beamed in daylight through domes to bounce around the walls with strategically placed inset mirrors and glass. Soane so hated the gloom of coal-smog London that he denied visitors entry to his home when it was raining.

Frank Gehry, who is every bit as fastidious about light, says the time to see the silvery titanium Guggenheim is just after a cloudburst on a grey day. Like Gehry, Soane questioned architecture, and turned lumpy stone and stodgy plaster into a billowing, tensile membrane. "He was always adjusting the pressure of space," as Christopher Woodward says. Gehry opens your eyes to what is around you. Suddenly you see why buildings look as they do. The process of building is difficult to document, which is why so many architectural exhibitions are so boring. To use an 18th- century word, it is a conceit to show Gehry in the Soane drawing-room as though the architect's studio had just landed there. "Conceit" as in witty game, not in its 20th-century, pejorative sense.

`Frank Gehry at the Soane' runs from 7 May to 19 June at the Sir John Soane Museum, 13 Lincoln's Inn Fields, WC2A 3BT (0171 430 0175). Admission pounds 2. Open 10am-5pm, Tuesday to Saturday