Most cities have a reason. St Petersburg only has a cause. Most capital cities - and this one was Russia's capital for over two centuries - grew up around a ford on a river, or a steep crag easy to defend. But St Petersburg did not grow up round anything. Instead, it was created by a sudden bayonet-thrust of will.
The will was Peter's. On 16 May (in the Old Style calendar, 27 May in the new) 1703, he snatched a bayonet from one of his soldiers and made two cross-shaped cuts in the soggy turf of an island in the middle of the Neva river. "Here a city begins!" he is supposed to have said, but probably didn't. What he wanted, at this point, was a fort and then a harbour. It was later that he decided on a town as well.
Why here? There was nothing to be seen but a huge, shallow, racing river, a flock of low islands, an endless scrubby pine forest on both banks. There were no people to speak of, only a handful of Finnish-speaking fishermen and some Swedish prisoners that he had just captured.
But Peter the Great said "Here!" because this was where he was that day. In his war against the Swedes, he had reached the banks of the Neva near its outfall into the Baltic. He looked happily at the wide waters, breathed in the moist air, and said: "Now!" If he had waited a bit, he could have captured the ancient port-city of Riga, a few hundred miles to the west, whose harbour stays ice-free for much longer than the Neva. But Peter was not a man for waiting.
So, the foundations for what would become the Peter-Paul fortress were dug. The Tsar lived in a log-cabin on the island, still preserved. Soon he moved his naval shipyard down from Lake Ladoga and built a naval base on the south bank of the river, the "Admiralty". Then, Peter wanted proper permanent stone buildings, including a cathedral, and he brought in the first of the foreign architects who designed St Petersburg over the centuries. Domenico Trezzini set to work, in the Dutch-baroque manner. The Peter-Paul cathedral began to rise, with its 400ft spire (more of a spike dipped in blinding gold). Other impressive buildings followed. Peter sent for his family and then for the court nobility from Moscow. They were ordered to settle in, and pay for the construction of their own mansions.
St Petersburg was not just one of those greenfield capitals, such as Washington or Brasilia. To begin with, there was nothing nobly natural about its site - waterlogged mudflats subject to floods and ice-bound for five months of the year. Secondly, it must be the only capital to have been founded on enemy territory, for Peter's final victory over the Swedes at Poltava, and their expulsion from Russia's north-western coast did not happen until 1709. Third, absolutely nobody except Peter himself wanted it.
The royal family and the Russian aristocracy hated the place. At first, they could not believe that Peter was serious. The climate was awful, there was no food (provisions had to be brought in by cart and sledge over great distances), and sentries were occasionally eaten by urban wolves. Even worse, there was water everywhere. Unlike Peter, whose passion was sailing and boat-building, most Russians were total landlubbers. But they came, under orders, and settled. Peter had a habit of punching people who were slow to obey him. One did not say "No" to this man. The Tsar was the most drastic moderniser in European history before Stalin, but he was also the ruler who had taken part in the mass torture and execution of the "Streltsy" mutineers a few years before.
After the battle of Poltava, Peter said: "Now, with God's help, the final stone in the foundation of St Petersburg has been laid." The construction of the city moved into higher gear, and more foreign builders and engineers arrived. Peter famously intended the city to be a window on the modern world, and one un-Russian, "European" style of building succeeded another. The Tsar's first idea was "English houses", which meant the half-timbered structures he had seen in London. But they were hopelessly flammable. Soon, Dutch and German styles appeared, as stone palaces and mansions were ranged along straight streets, plastered in the colours of the winter skies. A century later, the Marquis de Custine called it "Lapland in stucco".
Meanwhile, Peter decided to slice a pattern of urban canals through some of the main islands; Petersburg would be the Venice of the North, or better still, the Amsterdam of the East. He brought in the architect Alexandre Le Blond from Paris as head designer. The canals on Vasilevsky Island were dug and bridged while Peter was away. When he came back, he found that they were too narrow, and ordered the whole island to be reshaped following a fresh street-plan.
But how were the new citizens to get from one part of this archipelago to another? At first, Peter refused to allow any bridges across the main Neva channels. Russians, he decided, must learn to be seamen and get to work by sailing their own boats (no oars allowed). The poor were granted public ferries, but scores drowned because the peasant-ferrymen had no idea how to cope with winds and currents. Only when the Polish ambassador sank in one of these disasters did Peter agree that in future, the ferries could carry oars.
The Tsar himself had his own vehicle. This was a rowing-boat, which could be mounted on a horse-drawn sledge. If the horses and their drivers fell through the ice, Peter could run out the sculls and paddle serenely on. Why not? He was in a hurry to make his city not just a window on Europe but a wonder for Europe. He sent for quantities of flowers and scented herbs from Moscow (peonies, apparently, did well). Then he ordered up 8,000 songbirds. Some were released and others kept in an aviary, but most of them are said to have died.
So did human beings. All through the last three centuries, there have been disputes about how many lives the building of St Petersburg cost. After Peter's death, people guessed at 100,000, but historians now think it was less, at around 25,000-30,000. There was reticence on this subject during the Soviet period. Well there might be! In Stalin's time, too, an autocrat built colossal projects on rafts of human bones. In 1705, as in 1935, the labourers died of cold, exposure, hunger and pandemic dysentery. But at least the Petersburg workers who survived could settle in the city, and at least they were building something of enduring value and beauty - in contrast to the useless White Sea Canal. Foundations were often laid on innumerable crates of stones, dumped into the freezing water until a platform was established. And there was no stone in the area. It had to come from great distances, and at one point Peter banned all stone house-building in the rest of Russia in order to force trained masons to migrate to St Petersburg.
But Peter was happy in his city, even if few others were. A restlessly physical man, he loved joining in manual labour, wading into the water to rescue boats in trouble, turning wagon parts on a lathe, hammering on roofs, even firefighting. "It is a common thing to see the Tsar among the workmen with a hatchet in his hand, climbing to the top of the houses that are all in flames," said one visitor.
Best of all, he liked to take the tiller as his yacht skimmed out of the Neva estuary into the open sea. For Peter, the joy of Petersburg was its sense of space and possibility, which ancient, cramped, sinister Moscow could not offer. He wrote in a letter about "this paradise... truly we live in heaven..."
It is a strange thing that cities that have grown organically are somehow human, whereas cities created by an act of will feel inhuman. St Petersburg is superhuman. Peter did not think in terms of mortal men and women and their needs, as he supervised the town's design.
He was himself a huge man, 6ft 7in tall in an age when height was rare, and although his shoulders were narrow, his hands were calloused and vast. (There is a bronze cast of Peter's hand in the fortress at Azov, and it's as big as a gorilla's). He left a city built for an imaginary race even taller than he was. To feel normal in these streets that are wider than most squares, and in these squares that are larger than most parade-grounds, you would have to be about 8ft tall. Neither does Peter's architecture take account of weather. Older sub-Arctic towns huddle down into sheltering lanes. Not this one, although it is on the latitude of Churchill on Hudson's Bay.
This is what I see when I remember St Petersburg/Leningrad. A pale boulevard, which would take 10 minutes to cross, running straight to the horizon for mile after mile in a diminishing perspective of classical façades. Down this boulevard, a steady ice-wind driving from the Pole, whisking powdered snow across a river frozen hard as steel. I see the parapet of the Neva embankment, made of coarse-grained granite blocks the size of railway-wagons that glitter with mica crystals. Above me, what the writer William Gerhardie called "a small fugitive red sun". Two gleams of liquid gold, on the Peter-Paul and the Admiralty spires. This is like the Byzantium of W B Yeats ("I hail the superhuman"), where "a starlit or a moonlit dome disdains / All that man is, / All mere complexities..."
But only a foreigner feels like that. Nearly five million people are at home there. And - incredibly - they talk about it as a big village. For them, Petersburg is a cosy and intimate place where little things - a basement shop round the corner, a back court with a flowering bush, a circle of women friends living along the same canal - give the city its real character. They love it deeply, and its awesome scale makes them proud, not daunted.
Petersburgers think that they are special. This is not because they live in a "window on Europe", which in reality has been bricked up since 1917, and is not properly open even now (Moscow has become the post-Communist gateway to the West). And it is not because of their city's unearthly beauty. It is because they know how to stick together in hard times.
And there have been so many. Cruelty was always at home here. (Even in Petersburg's jokes: the Empress Anne made a bridal palace of ice for the court idiot, complete with an ice bed for the couple's first night). In 1825, the tyrant Nicholas I turned his cannon on the "Decembrist" mutineers on Senate Square, and filled the Peter-Paul fortress with democrats who had to watch each others' executions. In 1905, Cossacks slaughtered the workers asking for bread and freedom. After the 1917 Bolshevik revolution in "Petrograd", the middle classes fled abroad and the city froze and starved.
Renamed, Leningrad became the target for the worst of Stalin's terror purges. And then, in 1941, came Hitler's armies and the great siege, lasting over two and half years, in which as many as a million people may have died of cold and hunger.
Women, above all, kept the candle of humanity alight in the city's terrible 20th century. Circles of friends shared the last rotten potatoes, brought up the children whose parents had been arrested in the night, buried the corpses frozen under the snow in the courtyard. When someone had lamp-oil, the women read softly to each other from the work of Pushkin or Gogol, or from the forbidden poetry of Marina Tsvetaeva. In frosty rooms, they wore mittens to turn the pages.
The streets are granite, the palaces are marble, the statue of Peter the Great is a bronze horseman. But the ordinary people of St Petersburg, for so long a blur of extras and scene-shifters offstage, are tougher than any of them. They have inherited their city at last, from tsars, dictators and mafia bosses, and they are its best monument.
St Petersburg - a city firmly on the tourist map
Russia's second city was always a linchpin of the (over) organised holidays that kept Soviet tourism in something akin to business through the 1970s and 1980s. Groups sympathetic to the Soviet regime were offered ludicrously cheap trips, such as £500 for one month exploring the entire USSR, board, lodging and dodgy internal flights included. The tours usually ended at the city now known as St Petersburg. After weeks of viewing tractor factories in Omsk or Tomsk, British tourists were pathetically grateful to arrive in Leningrad.
The city was as close as the USSR got to the high life. Never mind the astonishingly rich architectural heritage, you could conduct illicit transactions with shadowy figures, and board the Aeroflot flight home jangling with Soviet army memorabilia and cheap "champagne".
But tourism to Russia slumped after the break-up of the Soviet Union. It was no longer compulsory to endure re-education, and vast tracts of formerly "closed" territory were opened up to visitors. Yet a lack of official enthusiasm for tourism meant that Russia missed out on the sharp rise in tourism through the Nineties.
Travellers can now take cheap flights to Niederrhein, Haugesund and other places that are not natural city-break territory. By comparison, St Petersburg's stature is evident: just one of its Baroque canal-side façades can trump most other cities, let alone the magnificence of the Winter Palace or the cathedral of Saints Peter and Paul.
Vladimir Putin, St Petersburg's most notable son, cannot be accused of racing to exploit the wonders of his home town. Just when the city could cash in on the tri-centenary, the Russian President is closing the it to all but invited guests for the duration of the celebrations. Perhaps this is a trick designed to enhance further the status of St Petersburg. By emphasising that some city breaks are more equal than others, the move could fuel a rise in discerning, high-spending visitors.