'I HAVE hardly had one hour to myself this week,' Francis Colman, the British minister to Florence, complained in 1725, 'by reason of the great concourse of English gentlemen that are here at present, of whom there have been above twenty.' Seven years later the ambassador in Paris, James, Earl Waldegrave, echoed Colman. 'The town swarms with English,' he wrote. 'I had near a dozen newcomers dined with me yesterday, and shall have near as many more today.'

One year in the 1730s, 12 English tourists were recorded in Turin, 34 in Bologna, 40 in Rome. From time to time between 1744 and 1772, Sir Horace Mann, then British minister in Florence, noted the Britons there in letters to his friend, Horace Walpole: the number was never less than 12 or more than 60.

When Benjamin Disraeli visited Paris and Italy in 1826, he wrote home to his father that Florence was a city where 'real cheapness is to be found. On five hundred a year (you can almost hear the wonder in his voice) you may live in a palace built by Michael Angelo (sic), keep a villa two miles from the city with vineyards, fruit and pleasure gardens, keep two carriages, have your opera box and live in every way as the first Florentine nobility.'

Disraeli had been sent abroad on what was a recognised part of the education of a well- brought-up young Englishman: the Grand Tour. Jeremy Black, in his recent book, The Grand Tour in the Eighteenth Century, makes it plain that there was no set pattern to it. Young noblemen and gentlemen were sent off, usually with tutors known as 'bearleaders' - appropriately, in view of the uncouth pranks the young gentlemen got up to. They took different itineraries, had different motives for travelling and stayed abroad for anything from a few weeks to several years.

The British Grand Tour frequently visited the Low Countries and the German Empire. Some adventurous spirits went to Russia, where one traveller was shocked by 'a monstrous scene of beastly women and indecent men mixed together naked' in a bath house; and even to the Ottoman Empire, where the Rev Robert Stockdale was surprised to find that he was not as shocked as he had feared by 'the first impalement we had seen'.

The great majority of 18th-century travellers, though, went to Paris, then to Italy, usually by way of Switzerland, whose mountains and lakes were just beginning to form the Romantic sensibility. They spent most of their time in the great capitals of ancient and Renaissance art: in Milan, Venice, Florence, Rome and increasingly, as the fame of its landscape and soft climate spread, Naples.

The opportunities the Grand Tour offered for gambling, drinking and especially sexual intercourse were not neglected. Paris and Venice were particularly prized for their sexual freedom, and the young gentlemen managed to get involved with princesses, countesses, opera singers, innkeepers' daughters and endless prostitutes - from the courtesans of Venice, reputed for their skill, to the 'votaries of Venus, for the most part of the lowest class', who thronged the Tuileries gardens in Paris after nightfall. Venereal disease was a constant danger and preoccupation; one young gentleman announced that he preferred women who admitted they had the clap, since their honesty meant it was less likely they had the pox.

Still, if high-blooded young British noblemen took advantage of the opportunities for debauchery abroad, it was not as if they had to go beyond Covent Garden to find sexual adventure, and their letters home suggest that they were also thrilled by the architecture, painting, music and statuary they discovered on their travels. The Grand Tour was one of the chief conduits by which Italian and French taste, and the influence of classical antiquity - whose Italian ruins were so much more common and more imposing than those farther north - reached Britain.

There is no doubt that a law of diminishing returns applies to today's tourism. When a traveller - a Byron or an explorer such as Richard Burton - took his life in his hands to visit Greece or Arabia and spent several years learning the languages and exploring the countries, he was profoundly transformed by the experience. We still have travellers, but more often we have tourists. The latter, whose visit lasts a week, or at most two, who needs to learn no more words of a foreign language than beer and wine, please and thank you, Ladies and Gents, is hardly touched by the experience. Indeed, a kind of 'factorisation' has taken place: as travel has given way to tourism, more and more people spend less and less money in seeing fewer and fewer sights in more and more places. Most of us have travelled like this, simply to get away from home.

But travellers do still exist and their numbers appear to be growing. More and more people are seeking adventurous holidays abroad - and not just those under 26. They want a deeper understanding of what they see. They do not just want to spend their days on the beach and their evenings in a hotel. And, increasingly, they are setting out to explore India, South-east Asia, South America, the Australian Outback or the Great Barrier Reef.

But while these exotic destinations were being uncovered, one region much closer to home remained a closed book. Europe meant Western Europe. Inter-Rail meant France, Germany, Italy, Spain - and Greece if you were enterprising. Then the Berlin Wall came down. Suddenly countries hidden behind a mental block became real places once more. Europe meant all of Europe, including those cities and countries whose history we had studied at school until they became frozen in a time-warp 50 years ago. Cities such as Prague and Berlin and St Petersburg picked up the threads of their past and came back to life.

Now Europe, which seemed the tamest destination, is the new continent to explore. Today, and for the next two weeks, I am proposing a new version of the Grand Tour: a modern version of the journeys our forbears made. Like the original, it offers travel for enjoyment and enlightenment. You can, after all, eat and drink as much as you can afford, like the bearleaders and their wards; and the briefest stay in any of Europe's great cities will convince you that neither love nor sex has been abolished.

The Grand Tour, in Georgian times, was directed not so much at understanding the contemporary world as at learning something of the history of European culture. In the 1730s or even the early 1800s, that culture meant, above all, the classical antiquity of Greece and Rome, the artistic achievements of the Renaissance and the Baroque in France and Italy.

But where the Grand Tourers of the Augustan Age went to inspect the ruins of the ancient world and to admire the work of the Renaissance, today's travellers will probably want to explore more modern shrines. They may seek the streets where the action of a novel by Dostoevsky or Kafka took place, or trace the evolution of architectural style from Art Nouveau to Post-modernism, or stand on the sites of the 20th century's great events, from the October Revolution to the fall of the Berlin Wall.

A New Grand Tour, to open up our own past, ought to move on. It ought to explore the buildings and the books, the art and the ideas, the cultural and political conflicts of the century-and-a-half since the traditional Grand Tour was made obsolete by the coming of the railways. There is no shortage of European cities to choose from: Stockholm or Athens, Dublin or Amsterdam, Vienna or Madrid. There are 'second cities' well worth exploring, such as Barcelona and Milan. And that is before you go east to Budapest and Warsaw.

I chose five of the greatest cities in Europe. You could visit them all inside a fortnight. Or you could do what I did, and visit each one separately for a few days. They are all cities where a visitor interested in having an enjoyable holiday, but also in learning something from it, cannot fail to feel the living presence of European history. Where better to begin than in St Petersburg, a city built primarily as a gateway to Europe. From there the New Grand Tour goes on to Berlin, Prague, Rome and Paris.

The tour itinerary

THE IDEAL way to visit the cities of the New Grand Tour is by train: fly to St Petersburg, then take the train to Berlin; via Warsaw to Prague; via Munich and Milan to Rome; and back to Paris, either direct via Switzerland or by going to Marseilles and jumping on a TGV.

Of course, you could also take the car to the Hook of Holland and drive the whole way - I know a couple who did almost exactly that last year - but it would be expensive. A compromise would be to take a return flight to St Petersburg, then fly to Berlin, drive to Prague through Saxony and the mountains of northern Bohemia, then fly to Rome and on to Paris.

What I did, to save time and money, was to visit each city by air. There is a silly reason for this: Apex tickets are much cheaper if you spend a Saturday in your destination city, and you must return to Britain between each flight. In the case of London-Paris, my ticket cost pounds 108; if I had changed it by so much as one hour, it would have cost me an extra pounds 92. In the case of Rome, the penalty would have been correspondingly greater. The total cost of my flights - London-St Petersburg-London, London - Prague - Berlin - Prague - London, London-Rome-London and London-Paris-London - came to pounds 767.50.

(Photograph and map omitted)