You know that a city has soaked right through into your soul when, after four drippingly wet, raw days in the dead of winter, you can't wait to get back. Suddenly, there's a hole in the protective lining that's supposed to keep seriously over-exposed places from getting mixed up with pocketfuls of Wanderlust. You find yourself flicking straight to the right page in the brochures, plotting a return. That is what happened to me with Venice.
December again - but this time there was the loyalty reward of sunshine. The gondolieri, stomping to keep warm by the water's edge, were wearing shades; one of them was even sporting a boater above green woollen ear muffs. Along the narrowest canals, nets of oranges dangled brightly from open shutters, and the water which had looked so black and ominous before shone like eau de nil lacquer. Three minutes and I thought: yes! Worth getting up at dawn, worth the dreary trek through Gatwick, worth the ripoff motoscafo fare to spin across the sea from the airport to this medieval kingdom with no cars.
And not many people, either - that's half the beauty of Venice in the winter. The fabric of the city - floating or sinking, depending on whether you're a fantasist or a realist - delivers the rest. Not until you are there, gaping open-mouthed at the extraordinary palazzi - galleried Byzantine, delicate Gothic, stately Renaissance, exuberant Baroque, all magnificent even in their damp dilapidation - can you see what all the fuss is about. And then you feel it isn't fuss enough. Sprinkled along narrow, ancient streets, buildings like these are compelling. Lined along the sweep of the Grand Canal, in one continuous ribbon of architectural history reflected in the water, they are beautiful beyond belief.
Ethereal, unreal - that's how Venice seems in the quietness of winter. You can cross St Mark's Square at dusk, when the shop windows full of Murano glass are all lit up and glowing like jewel caskets - and hear only the sound of your own footfalls in the vast, echoing piazza. Somewhere along the way, classical music will drift from an empty courtyard. Church bells will ring with a muffled, distant clang in the evening mist.
On both visits I set off at various times to see at least some of the sights - the lugubrious Doge's Palace; the tiny Bridge of Sighs; the inside of St Mark's which, with all its shimmering mosaic, was rather like standing underneath a giant gilded lampshade. Last time there was an exhibition on Casanova in the Ca'Rezzonico, the incredibly grand palace bought by Robert Browning in 1888 - the year before he died of bronchitis - and since converted into a museum of 18th-century Venice. The time before, the Peggy Guggenheim Collection was a treat - a modern art museum on a domestic scale, with works by Jackson Pollock, Kandinsky, Brancusi and many more displayed in the bright rooms of the palazzo where the flamboyant millionairess lived from the late 1940s.
But these are not the things that float into my mind when I think of Venice now. The picture is all fuzzy at the edges - dreamlike. I remember the hazy outline of Santa Maria della Salute, the massive church that stands guard by the entrance to the Grand Canal, looking, Henry James thought, like "some great lady on the threshold of her salon": it always seemed nebulous, to me - the sort of place you would hesitate to set off towards in case it might disappear like a mirage. Even the Christmas decorations - simple red stars strung across the streets - seemed from another world.
I thought I'd lost touch with reality completely, strolling one chilly afternoon along the wide quayside of the Zattere. Even though the temperature seemed down around deep-freeze level, there was a queue outside Gelateria Nino - Italians in fur coats, impatient to wolf down ice cream. And then I stumbled on a gondola boatyard - an arrangement of wooden chalets which looked as if it might have leapt straight out of some Tyrolean legend. Worrying, until it came to light that both the timber for the city's black boats and the craftsmen to work it had their origins in the Dolomites.
I couldn't quite bring myself to arrange a gondola ride - too touristy, maybe, or just too damned cold. But I loved watching these curiously asymmetrical boats which have been around for a thousand years, negotiating even the narrowest waterways. Apparently only about 10 are built now each year - a painstaking process involving rigidly traditional techniques, nine different kinds of wood and seven coats of paint.
Walking in Venice is pure bliss - especially in low season, when there are no crowds to choke the slender streets. "The Venetians walk everywhere," said our local guide, urging us over the hurdles of a score of those steep-sided little bridges at speed. "They are very healthy, you know? They don't break their hearts."
In the cardiac sense, maybe not. But how heartbroken would visitors be if they missed the chance of gliding through this city's magic by water? Take the vaporetto - one of the rusted, cream waterbuses that ply the main routes. You'll gain a whole new perspective on a place that still conducts its most important business afloat. In a sporty-looking boat, the revenue commissioners whip past barges laden with fruit and vegetables, Christmas trees, the refuse collection.
Coming back late one night by vaporetto from a dinner that must have featured seven or eight delicious kinds of Venetian sea food in the same number of hours, the lagoon was black and silent, the gaily striped mooring posts barely visible; only the landing stages and a handful of hotels cast out intermittent light. Every time we reached a stop, the awful screech of engines in reverse rent the still night air. It was the ghostliest of journeys. But, back on terra firma in San Marco, the Somalis selling Prada fakes were still there - still hustling hard. "Those bags are made in Morocco," somebody said. "Hmmm," murmured our Italian host. "Or Naples." Reality after all.