Once we had a planet. Now, at the start of the third Christian millennium, we're left with a suburb.

In our world, you can fly from any big city to any other in 24 hours or less. A few rogue places exist to which you can scarcely fly at all, but their number is going down all the time; as I write they include North Korea, Chechnya, Afghanistan and Somalia. Libya was taken off the list in 1999, and a dozen big international airlines immediately started flying to Tripoli again.

When, following the collapse of Communism, an American academic made himself famous by announcing the death of history, most of his colleagues disagreed. A decade later there are scarcely 20 countries which haven't adopted the politics and economics of liberal democracy. If it isn't quite dead yet, history, in the sense of a clash between different political concepts, does indeed seem to be withering on the vine.

Our world has been mapped with complete accuracy, and there can be scarcely any peoples or species left uncatalogued. In 1999 a surprisingly large new species of tree rat was discovered in Peru. The previous year two separate bands of unknown wandering tribesmen were discovered in Papua New Guinea. They possessed no spoken language, and conversed solely in signs. In the dense forest in the far west of Brazil I came across a man who had found the arrows of various different groups of Indians unknown to ethnography. Groups in the Congolese jungle or the Kalahari Desert have probably not made contact with the outside world. But that is just about all. There are more people alive now than in the whole of mankind's past, which creates problems for those who believe in reincarnation. Yet for the first time we all know one another.

Worse, the differences between us are disappearing as fast as the animal, bird and insect species we share our planet with. In the 1960s you could still work out where you were when you drove across the United States by the accents and the food; not any longer. In the 1970s French was still an important second language in countries as divergent as Iran, Yugoslavia and Romania; alas, for those of us who have laboured to improve it over the years, not any more. An inalienable sameness has settled over the globe. The spirit of place is evaporating fast.

We are losing our distinctiveness, our human biodiversity, with appalling speed. As Gertrude Stein wrote of Oakland, California, 'There's no there there.' We tend to think of the process as being American-inspired, but it is merely American-led; the United States has gone farther and faster down this particular road then the rest of us, that's all.

Europe is doing its utmost to catch up. The powerful sense of regional identity that used to exist throughout Europe has faded very quickly. The first time I stayed in Venice in the early 1970s I remarked to the old lady who was showing me to my room in the Pensione Seguso that there were a lot of tourists about.

It was as if this was something special to the city, which those of us who lived elsewhere wouldn't necessarily appreciate.

Not long afterwards I spent a weekend on the charming Ile St Louis in Paris, and needed to buy a bottle of ink to write some letters.

The Ile St Louis is about 50 metres equidistant from the Left and Right banks of the Seine. Nowadays it is full of twee shops selling crêpes and glove puppets and paintings by Bernard Buffet, and English buskers queue up on the bridge, waiting for their half-hour turn in front of the tourists. Then it was a separate place with its own clearly established sense of identity.

All but two or three of those specialities can still be found in France, though European Union regulations make it illegal to sell even Brie and Camembert if it is produced in the strictly traditional method. France, once the most idiosyncratic, regionally diverse and uncontrollable country in Europe, is settling into the same uniformity as the rest of us. There are Body Shops and Holiday Inns in large numbers there too, and more McDonald's in Paris than in London. Obesity, the defining disease of Western man and woman, distinctly hamburger- and Coke- related, is beginning to affect France as it has long affected Britain. As for America, airlines are beginning to introduce wider seats to accommodate the growth in American arse sizes, and lavatories are being manufactured two inches wider.

In other ways, too, the choices are lessening. Until about 1980 furniture shops in Wales sold what was known as 'the Welsh bed', wider and shorter than the types available in the rest of the United Kingdom. Officially, we are all the same size now. And we are all equal in the face of technology. There was a time when, travelling abroad, I could go for days without contacting my office. Now I am fortunate if more than a couple of hours pass without a call from London; even during the night, if they forget about time difference - the one major element of distinction between one place and another that no one has yet suggested ironing out.

When the local telecommunications system doesn't run to the use of mobile phones - and I have used one to call my office from the Khyber Pass, the Great Wall of China and the flat of a drugs baron in Medellin - then I can always take a satellite phone the size of a small briefcase with me. In the 1970s my foreign desk used to communicate with me by telex. The technology was untrustworthy and the language strange:

("Ga" stood for "go ahead.")

By the late 1980s the office sent me faxes, though they were on a shiny paper which curled up, and the words faded fast. If you went into the hotel business centre, another '80s concept, and asked to use a desktop computer, you would never know which of a dozen or so types of software it might use. Now, from Damascus to Lahore to Xian, everyone uses Microsoft. Sometimes you have to work out how to get out of Chinese or Arabic characters and into Roman ones, but that's all. It probably won't be long before that little nuisance to the manufacturers is ironed out too, and everyone will speak and write a kind of English.

Convenience has driven out variety; and not merely in the hotel business centre. Which American mall doesn't have its JC Penney, its Radio Shack, its Häagen Dazs? Which British high street doesn't have its Marks and Spencer, its WH Smith, its Principles? And when you come across these shops abroad, your first response is not a pleasant flash of recognition but a dull sense that you haven't really reached anywhere different after all.

In the Yemeni capital, Sana'a, there are almost as many mobile phones per capita as there are in New York City. In Bokhara and Samarkand you can buy hamburgers and hot dogs on the street corner. In the remotest reaches of the Amazon the children who play in the dust wear T-shirts with the Nike or Coca- Cola logos. In Iran, I have seen posters advertising a Sylvester Stallone film on the walls of the holy city of Qom.

The feeling is growing, especially in the United States, that there is no need to travel abroad, since abroad is travelling to you. In Washington DC I have been driven by a taxi driver who had been the leader of an Afghan mujaheddin group, and in Paris by another who had been an Iranian air force general. In Denver I once found a taxi driven by a North Korean who spoke not a single recognisable word of English, and in New York City a taxi driver from, I think, Equatorial Guinea, who had no idea where or what Wall Street was.

In London there are colonies tens of thousands strong of Colombians, Thais and Ethiopians - people without the remotest colonial links to Britain. There are Japanese restaurants in Kinshasa, Beijing and Geneva, and Italian restaurants in Amman, Minsk and Pretoria. You find the best Thai food in the world in Australia, the best balti in northern England, and the best Persian fesanjun in Los Angeles. Tandoori has become the quintessential British dish, while curry has supplanted fish and chips as the most popular take-away food. Hamburgers are far more popular among the 13 to 18 age group in France than steak-frites or magret de canard.

Once, caught unexpectedly in St Petersburg, I had to kit myself out at short notice from head to toe from the local Hugo Boss shop (the original Hugo Boss, incidentally, prospered in the 1930s and '40s as a tailor to Himmler's SS, and still seems to favour black). I then found that half the members of my audience of Russian literati and local politicians were also wearing Hugo Boss clothes.

That's good for business, of course; biodiversity costs money, but sameness encourages economies of scale. Fortunately for the big corporations, everyone everywhere seems to want exactly the same thing: Sony Walkmans, Adidas trainers, Toyotas, Swatches, caps with the peaks worn at the back. (When I was on The Spectator we ran a cartoon which showed a teenager asking a salesman, "Have you got any of these with the peak at the front?").

There are only a handful of places left on earth where you can escape all this; as I write there is no McDonald's in Cuba, no Coca-Cola in Libya, and no television in Afghanistan. But in order to find real difference you have to travel well outside the political pale. If you want to get away from the English football results and USA Today and advertisements with Cindy Crawford or Sir Anthony Hopkins in them, you must take your courage in both hands and go to the few really difficult, independent, unpredictable places which are left.

Sooner or later even these last sandcastles of independence will be washed over. The Havana Libre Hotel will turn back into the Hilton, Tripoli will have Häagen-Dazs ice-cream parlours, Afghanistan will tune in to Friends, restaurants in Iraq will accept payment in Euros, and earnest tour guides will lead you in total safety across the dividing line between north and south Mogadishu to a Holiday Inn or a Sheraton. How wonderful, I can't wait.