Fasten your seatbelts, suspend disbelief ... this is La$ Vega$

In the trompe l'oeil that thinks it's a city, you can spend your days buried in a pyramid, your nights at the Round Table and spend nothing on entertainment. The world's greatest conglomeration of light bulbs is an unnatural high, as Simon Calder found when he checked in to Vegas - and checked out of reality.

Imagine. This year, your birthday and Christmas have arrived at once. Your parents have bought the entire stock of the local toy shop, invested in an extra set of heavy-duty batteries and installed the lot in the sunniest place in the world.

If you think that notion sounds preposterous, just wait until you see Las Vegas. This ludicrous city takes tourism to its gloriously illogical conclusion, and invites the world to a party as endless as the summer.

The moment you realise that reality eludes this corner of the Nevada desert is when, in the midst of a kitsch Arthurian concoction called Excalibur, you see a sign indicating "Moving Walkway to Luxor". The mobile sidewalk wafts you from a climate-controlled version of the English Dark Ages to an equally air-conditioned epitome of ancient Egypt - residing in a hotel- that-thinks-it's-a-pyramid, protected by a vast, grinning Sphinx.

Luxor is as good a place as any to begin the vain but hugely enjoyable task of trying to make sense of Las Vegas. Forget any traditional notions of citydom - the place is really a succession of villages. They are strung out along Las Vegas Boulevard, a four-lane fury stripped down by everyone to the single-syllable "Strip". While each village is obsessively individualistic, they are all linked spiritually by a passion for absurdity.

The entertainment industry has staked many millions of dollars on creating this nonsense, and you, the visitor, are the winner. At other US airports, flights to the city show the final destination as La$ Vega$. Yet it is easily the cheapest place in America, with most of the attractions being completely free. You can stroke past the Sphinx, wander through the pyramid and take the moving walkway back (and forwards a few centuries) to Excalibur, gratis. Dinner at the Round Table costs more than a couple of groats - but not much more. Competition is as fierce as the heat from the constant sun, which means that you need never pay more than pounds 5 on an all-you-can- eat meal. Gluttony suits the 20th-century's biggest monument to conspicuous consumption rather well.

"Please fasten your seatbelts, return your tray table to the upright position and suspend your disbelief." Even if the stewardess doesn't say that on the final approach to Las Vegas, you will raise your credulity threshold anyway when the aircraft touches down beside Manhattan. Close to the runway, and adjacent to the Anglo-Egyptian complex, someone has seen fit to build New York New York - a hotel so gaudy they named it twice. Despite the collusion of the Statue of Liberty, Empire State Building and Chrysler Tower, you can tell you're not really in the Big Apple because a rollercoaster has wrapped its scary self through and around the counterfeit conurbation. Besides, Times Square and Central Park are protected by the giant ceiling that squeezes out the sun, creating a kind of Center Parcs for wayward grown-ups. All the usual dimensional reference points are distorted, and any hope of keeping a grasp of the space-time continuum is eliminated by the absence of clocks. Like Manhattan, this city never sleeps. But unlike the real thing, not a single villain is to be seen. You are more likely to be mugged in a nunnery than in New York New York.

Out again, beneath the ever-beaming sun, to investigate that vast green slab across the road. The MGM Grand is America's biggest hotel, but in case sheer size isn't enough to draw the crowds, it comes complete with theme park and monorail. Trains resembling silvery spaceships nose northwards, whispering past the shrieking victims of the SkyScreamer - a monumental cross between a garden swing and a bungee jump.

The train crews collect tickets, because of course there are none, but they do wear badges announcing their name and home town. No one, it seems, actually comes from Las Vegas. What you're dying to ask of "Bob, Boston Mass" and "Sue, Sacramento Cal" is why they should choose to leave their roots for a bit part in the theatre of the absurd.

Maybe they ran away to Circus Circus (so glitzy they named it twice?). When the sun finally beds down, beyond the mountains that guard Las Vegas from hostile reality, you can imagine the frowning engineers watching the meters down the road at the Hoover Dam. This hydroelectric facility struggles to supply sufficient power for the millions of lightbulbs that keep the dark desert night eternally at bay.

A good few thousand of them swaddle Circus Circus. Unlike the average Big Top, this circus is in fact a collection of awkwardly angular hotel towers. The hub, though, is a genuine and gratuitous circus: an arena hemmed in by sideshows. Athletic acrobats perform miracles, accompanied by musicians whose jaded expressions reveal, as clear as a coda, the knowledge that there is no hope of professional progress after tinkling the fake ivories at Las Vegas.

As Elvis Presley demonstrated, this is the right place to see musicians at the wrong end of their careers. Thirty years ago, Steppenwolf were born to be wild; this week they were judged tame enough to play Las Vegas. Nobody makes mischief around here, but if they did they might headline next Saturday's gig at the Rio "The Sounds of Senility"; like a bridge over troubled decades, Art Garfunkel will be crooning to the converted.

A ticket for Art will set you back pounds 12, a wiser buy than spending cash on a timeshare in a Deja Vu Show Girl - whose company boasts of "Hundreds of beautiful girls and three ugly ones". The prosaic address, 3247 Industrial Boulevard, emphasises that the dollar is the lowest common denominator for every transaction in Las Vegas.

Budget travellers have no need to splash out on ugly girls or ageing singers for entertainment. Defying the civic disdain for clocks, a precise timetable of performances is scheduled along the Strip. Five times a day, Russian gymnasts troupe out a jaw-dropping routine in which a performer perched on a single stilt is catapulted high into the clear desert sky to something approaching near-earth orbit. No safety net - Las Vegas is all about risk.

Every 90 minutes, Treasure Island stakes its reputation on the live "Buccaneer Bay Show", in which passers-by are invited to watch a platoon of English pirates (complete with cod-Oxford accents) do battle with a Spanish treasure ship.

If, by the time the British boat sinks and is miraculously resurrected, your mind is still battling to keep in touch with reality, the volcano that erupts along the street every 15 minutes will see off the last shred of sense.

Hallucinogenic drugs are expensive, illegal and dangerous. Las Vegas is none of the above, but has roughly the same effect. Oh - and if you wish, you can also gamble.

Simon Calder paid pounds 432 return on United Airlines to Las Vegas via Washington, booked through Quest Worldwide (0181-546 6000).

If you are not married when you arrive in Las Vegas, you could well be by the time you leave. The Las Vegas home page on the Internet lists 47 wedding chapels, from A Precious Moment to the Wee Kirk o' the Heather.

The Commissioner of Civil Marriages offers instant nuptials for $70 (including the licence), but for something more sophisticated you will need to shop around - and must expect to pay for romantic touches such as being married by an Elvis impersonator or aboard a hot-air balloon.

Ken Burleson, manager of the Chapel of Love, issues the following advice to prospective partners:

"Dear Bride and Groom, When I shop I like to know the total charges. So, I'd like to let you know up front exactly what additional charges there will be when you get married in Las Vegas.

"Licence fee $35 - the only place you can get a marriage licence is at the Clark County Courthouse. Cash payment is required.

"Minister's gratuity - the ministers in Las Vegas are not employees of the chapel. He will give you an envelope at the end of the ceremony. Suggested gratuity $25 and up.

"Limousine driver's tip - it is customary to tip the limo driver in Las Vegas, around $20 if the service is good.

"Sales tax - package prices do not include Nevada Sales Tax."