The Weasel: 'Authentic, exciting and unnerving,' claims the waxworks. 'It is not intended to be gratuitously frightening' - which, of course, is precisely what it is

The completion of a pounds 1-million refurbishment of the Chamber of Horrors provided Mrs W and me with an excuse to play tourist for the day and visit Madame Tussaud's. Such is the lure of celebrity, even in replica form, that at peak times about 20,000 people a day are attracted to this peculiar institution. Having had the foresight to book tickets in advance, we missed the pleasure of queuing for around one-and-a-half hours on the hamburger-scented pavement of Marylebone Road. Since most visitors were from the Continent, it is hard to imagine what they made of the first waxwork we met on emerging from the long, claustrophobic staircase. There he is, dropping a tray of drinks, his Latin features contorted in panic - Manuel from Fawlty Towers. But this xenophobic caricature is balanced by two adjacent figures who, in their own ways, sum up much about modern Britain: Arthur Scargill and Terry Venables. Nearby, in a tableau of striking incongruence, Lester Piggott glares up at Grace Jones. Though more or less mystified, the visitors dutifully produced video recorders in order to capture any movement by the tallow celebs.

While Tussaud's huffs and puffs about the unstinting efforts of its artists to achieve perfection in their simulcra, the fact remains that some of the figures on display are far from convincing. With the addition of a lick of eau de nil, Dwight D Eisenhower would be a spit for the Mekon. If the waxworks ever decides to do away with Ronald Reagan, it would merely have to remove a few inches from the legs for the figure to gain a new lease of life as Hollywood heavy Joe Pesci. In many cases, it scarcely matters whether the figure is realistic or not. Few visitors would be able to ascertain the accuracy of King Harald V of Norway or the Marquess of Salisbury (1830-1903). Despite the royal family's willingness to pose ("often more than once, to keep their figures up to date"), the regal line-up is no great shakes - I doubt if the Duke of Edinburgh would admire his somewhat portly facsimile - but the progressive displacement of Princess Di provides a lively conversation topic for regular visitors to Tussaud's. If the Queen is the centre of this majestic solar system, Diana is now Neptune. (A touch unfairly, Princess Margaret acts as Pluto.) Fergie, however, is nowhere to be seen, banished to the outer darkness - or, possibly, the melting pot. Maybe it was too much trouble keeping up with her constant change of image.

Eventually we reached the object of our visit. It seems that the recent outlay on the Chamber of Horrors mainly went on an amplification system which produces a headachy cacophony of screams and clanking chains. Tussaud's is understandably ill at ease about this tacky display of Grand Guignol. "Authentic, exciting and unnerving," claims the waxworks. "It is not intended to be gratuitously frightening" - which, of course, is precisely what it is. It comes as a great relief to pass the final exhibit: "Dennis Nilsen - the Muswell Hill Murderer". A remnant of an era when executions were a public spectacle and the lunatics of Bedlam were regarded as a laughing stock, the Chamber of Horrors is seen by 2.5 million visitors each year. But can Tussaud's proprietor, the Pearson Group, which also owns Penguin Books and the Financial Times, really be proud of this sordid outpost of its empire?

After Tussaud's, London's second-longest queue is at the Tate Gallery. When your timed ticket eventually gains you admission, the Cezanne exhibition is hot, crowded and fetid. The works are every bit as wonderful as the critics (barring the preposterous Paul Johnson) promised. But am I alone in thinking that the art scribes don't give a full account? They see the exhibition during the press view, when the galleries are virtually empty, with the crush of art lovers held at bay. Would a restaurant reviewer ignore the fact that the establishment where he was sampling the cuisine happened to be full to bursting? Or would a theatre critic omit to mention that a production was marred by the audience clogging up the proscenium arch?

In fact, it is possible to see Cezanne at the Tate without being jostled and prodded. Another exhibition in the building, Still But Not Silent, a selection of still lifes by an assortment of artists, includes an 1893 study of apples and a water jug by the great man. If it were in the big retrospective, the work would inevitably be surrounded by a peering mob of admirers. By simply walking across the corridor, not only do you have the painting to yourself, but you also don't have to pay.

If you're planning a trip to Greenwich, generally regarded as having the finest collection of buildings in London, better do it pronto. Though in summer the area is already as crowded as the Marrakech souk, the numbers are about to be swelled even further. Last week it was announced that a university is to be created in the former Royal Naval College. In addition, in case you'd forgotten, there's the small matter of the Millennium Exhibition, expected to attract 15 million people over a two-year period.

When she announced, a few weeks ago, that Greenwich had won the millennium competition, Virginia Bottomley alluded to its advantage of "being on the Prime Meridian", rather as if this were some natural phenomenon like the Grand Canyon. Visitors to the Old Royal Observatory in Greenwich Park tend to treat the line in the pavement which marks the meridian in much the same way - though they are probably a little hazy about why God chose this southeastern suburb of London as the dividing point between the two hemispheres. It must be one of the most photographed patches of ground in the world. People peer at it in baffled reverence, before adopting a special stance - a somewhat inelegant straddle - directly over the line.

The line is made of brass for a few feet in London SE10, but it runs notionally from the North to the South Pole. If tourists are determined to have their snap taken on 0 degrees longitude, they could also obtain satisfaction by visiting Tarbes in France, Tordesillas in Spain or Gao in Mali.

As a notice in the Observatory acknowledges, "a meridian is an arbitrary north-south line chosen by an astronomer". The line used by Greenwich's stargazers was adopted as the Standard World Meridian at an international meeting in 1884. It was not an easy decision, since many of the 25 countries attending the conference advanced the merits of their own meridian lines. In the end, however, a near-unanimity prevailed. For some reason, San Domingo - now the Dominican Republic - was the only country which voted against, though Brazil and France (d'accord) abstained. The French colony of Algeria only agreed to join in if it could express GMT as "Paris Mean Time diminished by 9 mins 21 secs". It is interesting to speculate that if Birmingham had been blessed with the foresight to send a delegation to the conference, the city might have been rather more successful in its millennium bid.

Sadly, the reason why Greenwich was adopted as the Prime Meridian in 1884 had nothing to do with the unswerving, decidedly non-kinky nature of the British line or its refusal to deviate, as, say, an Italian line might have done in search of a cappuccino. Its success stemmed primarily from the fact that most of the world's shipping depended on charts which used Greenwich as the Prime Meridian. Of course, that was when Britannia still ruled the waves. If the conference were held today, we'd probably be celebrating the millennium in the Dominican Republic