Friday afternoon rush hour. Four lanes of traffic are crawling north across the Golden Gate Bridge to weekend homes in countrified Sonoma or clapboard coastal cottages within earshot of the Pacific breakers. The two sparse lanes going in the opposite direction are hurtling much faster than I'd like, shuddering in my unfamiliar hire car across the surface of this perilously bouncy, petrifying structure strung out across the sky. The longest suspension bridge in the world - and the longest suspense. Is it wise, this mad dash to the city?
Oh, yes. San Francisco doesn't waste much time over courtship. It's a case of straight seduction. I'm an easy conquest, I suppose, because I have a long-standing weakness for America's big cities: all that showmanship and towering bravado. They're crazy, wacky places to whizz into for a few days and then flee.
But this is different. I could live here, enjoying a sunny existence in one of those little Victorian houses, prettified in pastels, that they call Painted Ladies. If ever I should go missing, this is where I'd be: in a quiet street somewhere between Pacific Heights and the sea.
That would be true to local tradition. Because, in the century and a half since the Gold Rush turned San Francisco into a wild frontier city full of chancers, it has been the world's asylum for people on the run from pressure of one sort or another; people who just want to vanish and start again.
"It is an odd thing, but everyone who disappears is said to be seen at San Francisco,' Oscar Wilde wrote in The Picture of Dorian Gray. And it has absorbed all the blow-ins with an upbeat, easygoing tolerance that hangs in the air like one of those scents supermarkets pump out into the atmosphere to make customers feel happy.
It is a convention of travel writing to describe every semi-attractive metropolis under the sun as a walking city. Amsterdam is one. Boston is one, if you've got Nike Air soles. Dublin pretends to be one - odd when you look at the traffic. But San Francisco is the genuine article, a place where only the most photo-obsessed tourists board the few cable cars the citizens insisted on keeping for old times' sake when buses arrived in the 1940s. The rest stroll.
My Saturday route starts with a tramp through Chinatown, a big and vibrantly authentic enclave tumbling out over maybe 20 blocks. A fifth of San Francisco's population is Chinese. Streets and streets of oriental bric-a-brac and shady dimsum parlours, Chinese herbalists, dressmakers, grocers and greengrocers with bigger woks, weirder vegetables, more pungently challenging spices than anything ever encountered with Ken Hom.
On the fishmongers' strip, sturgeons and catfish swim up against the window in their tanks of murky water. But they're not half as disturbing as the big wooden crates inside the door, packed with live toads.
Climbing up Russian Hill, after the riot of chinoiserie has given way to sedate residential calm, there's a chance to understand why so much is made of San Francisco's architecture. The guide books may lament the loss of scores of elaborate Victorian houses in the great earthquake of 1906 and the devastating fire that followed - the fanciful mansions of the grandees on Nob Hill were wiped out in great clumps - but thousands survive.
All over the city, you'll glimpse them, holding their elaborate cornices and turrets and pedimented doorways up proudly, not to be outdone by newer, brasher buildings. Gothic revival houses with pointy arches, Italianate houses with decorative plasterwork, tall, narrow `Stick' houses and the folly-like creations an inspired English architect in search of an evocative name baptised `Queen Anne'. . . you'd have to have a heart of stone - and seriously defective eyesight - not to be entranced by these exuberant survivors.
Time to pick up on basic sightseeing, heading through North Beach, the original Italian quarter, towards the waterfront. Next to Washington Square, a green patch of sunbathers and toiling artists, are the slender twin towers of Saints Peter and Paul, still known as "the Italian cathedral", on whose steps Marilyn Monroe and Joe Di Maggio had their marriage blessed.
This is close to the Beat neighbourhood, where Kerouac and Dylan Thomas fans go to pay homage. Or perhaps to check out the Condor Club, where the world's first topless stage show went on stage in 1964. Rumour has it that in a subsequent show the set collapsed, crushing the two in flagrante performers to death.
Would Fisherman's Wharf, the most relentlessly publicised bit of jetty on the planet, be worth a second glance, I wondered? Or just a place that draws in trippers and traps them there in torture, like a sort of giant lobster pot? There are buskers and popcorn stands and pedicab tours - yes; ticket touts for the ferry trip out to Alcatraz; and a long line of down-and-outs who seem to have decided they may score higher sums for the honesty of a sign that says "It's for the beer". There are also seafood cafes where crowds queue up for oysters, Dungeness crabs and sandwiches bursting with enough seafood cocktail to feed six people back at home.
But I rather liked it. I enjoyed sitting in the sun outside Boudin's Bakery, a San Francisco landmark since 1849 when one Isidore Boudin transformed the simple sourdough bread that had been a staple of the wagon trail into a crunchy, irresistible French treat. Fisherman's Wharf seems real in a way that few tourist honeypots do - maybe because there are still some fishermen packing their craft tightly into the working part of the harbour. And, because it has evolved slowly over 40 or 50 years, there's surprisingly little of that tacky fast-buck feel.
The legs are beginning to ache and there's no obvious way to avoid the notorious hills. So, fleetingly, it's not a walking city. It's a fast taxi town, guaranteeing just enough lingering sensation in the feet for a tour of the Museum of Modern Art over near the financial district with its forest of shimmering towers.
Designed by Mario Botta and completed just four years ago, San Francisco's MOMA is a pretty spectacular modernist building, funnelling light into an atruim through a giant, cylindrical skylight. Plenty of 20th century greats - Matisse, Brancusi, Mondrian, Klee, Picasso - are in the rotating permanent collection. But more exciting, maybe, is the opportunity for extensive immersion in American art. Two galleries, for instance, house works by Robert Rauschenberg - post-De Kooning and Jackson Pollock, preWarhol.
Time, now, to bask in the virtuous afterglow of a burst of culture, plunging with the speed of the damned into the palaces of retail therapy that completely dwarf the palms of Union Square. Macys, Saks Fifth Avenue, Nieman Marcus and, nearby, a Banana Republic as big as the Dail . . . . they are all there, waiting to part you from your dwindling dollars. Unbeatable American service finds you the size, the colour, 10 times over, with a beaming smile.
But San Francisco has another culture which you must not, indeed cannot, miss. Food is an obsession. The San Francisco Chronicle's coverage of restaurants and cooking runs to eight full pages - on Wednesdays, for heaven's sake.
There are 66 food programmes on TV here in a week - and probably six times that many good places to eat. I go one evening to Boulevard, where Nancy Oakes cooks up exquisite, all-American fare in the theatrical setting of the century-old Audiffred Building. Another I'm drawn to is Greens, a place that has proved for 20 years that vegetables can be dazzling, especially when the Golden Gate is a necklace of twinkling lights only yards from the plate.
It's just as well the hills are there as calorie-burners.
