In the days when Lent was a strict affair, when it meant forty days of fasting, prayer and no sex, the last few days before it began became party time. The name 'carnival' comes from the Latin carne vale, or farewell to the flesh. Forty days of abstinence stretched in front like an eternity of enforced celibacy, and forty days of no meat compounded the strictures. In the Latin countries of the Mediterranean basin Carnivale, or in French Mardi Gras, took on a little of the old Dionysian rites of pagan days, where feasting, drinking and a temporarily freer attitude to sex defined the feast. These days, when the demands of Lent are no more than a few days of trying to change a bad habit before giving up on the task, Carnival time has lost much of its urgency and here in Ireland the closest you get to a treat is a sugared pancake. But there are a few places in the world where it still means something; Rio, Venice and New Orleans.

I've yet to experience the excesses of Rio do Janeiro, but five days in New Orleans has given me a glimpse of what it might be like. New Orleans takes its French heritage seriously; it didn't become a part of the United States until the Louisiana Purchase of 1803, when the territory was bought from the French who had named it after the Sun King, Louis. Even then the city was known as a wild place, its position on the Gulf of Mexico and the Mississippi River ensuring that every smuggler, pirate, river-trader, prostitute and gambler could find a living in it. By the way, if you want to pronounce its name like a native, try to say 'Nawlins' with a drawl.

As cities go it's not big, somewhere around a million people live here in a low-rise skyline spread out along The Big Muddy's floodplain, between the sea and the huge Lake Pontchartrain to the north. Apart from the French influence, there's a little Spanish colonial inheritance, but the biggest cultural influence is Creole, giving the city a definite Caribbean flavour. Half-circled by a big, lazy bend in the river are two of the city's best known neighbourhoods, the Garden District and the French Quarter, which lie to the east and west of Canal Street respectively. Canal Street is one of the city's major thoroughfares, running from the river right up to Mid-City. When it comes to Mardi Gras you can take your pick; the wholesome, family-orientated parades which are mostly centred around Canal Street and the Garden District, or you can take a walk on the wild side and venture into the French Quarter for something more than a little different.

For the residents, much of the official carnival - a time that stretches from Twelfth Night right up to Mardi Gras - revolves around the 'krewes'. Back in 1857 a torchlit procession calling itself the 'Mistick Krewe of Comus, Merrie Monarch of Mirth' took to the streets with carnival floats and riders on horseback. Based on Milton's Paradise Lost, its members dressed as the demons of the poem, it brought to the festival for the first time the idea of a themed parade. Up till then the parades had been loose congregations of people, who threw mud and flour at one another. The 'krewe' idea was adopted at once, and most of the krewes of today still carry mythological names. All the krewes have a king and queen who reign over their court for the festivities and in recent years new 'super krewes' have come on to the scene, like Endymion and Orpheus, which feature flashy and expensive floats.

The parades are continual; most days leading up to Mardi Gras feature three or four, which vary in routes but mostly take in Canal Street at some point. Many of the floats reminded me of the floats we saw in Dublin years ago on St. Patrick's Day, simply made and pulled by a tractor. The Americans appear to have an infinite patience with marching bands, seemingly never tiring of watching an endless succession of overweight schoolchildren parading their instruments and gaudy costumes for hour after hour. The main feature of these passing floats is the 'throws', which can be plastic cups or coins, but are mostly strings of beads. Each krewe has their own house style of bead and there is some competition among the crowds in catching them, as costumed krewe members throw them into the masses as they pass. I watched this for much of an afternoon, but the less formal attractions of the French Quarter were more to my liking.

The French Quarter is the oldest part of the city, it's architecture pleasing to the eye and soul. Two and three-storey buildings are laid out in a grid of blocks, fourteen by six, with Bourbon Street running across the centre. Many of the houses have cast-iron balconies which are supported by pillars running down to the pavement. Some are elaborate and ornate, others more simple, but most of them are filled with hanging baskets of flowers and greenery. None of the formal parades pass through the French Quarter, but the tradition of 'throws' takes on another shape here. The balconies of Bourbon Street, and to a lesser degree the parallel Royal Street, are filled with people with armfuls of beads which they throw to the revellers in the street. It's hard to explain just how many strings of beads are here. All day, all night, there are people throwing beads and people catching beads. It's relentless and noisy and in true European snotty mode I wanted nothing to do with it at first, thinking 'God, how tacky.' But the odd thing is that after a bit you get infected, it's contagious, you're smiling up at balconies and running to catch strings of nasty plastic beads as though they were a prize worth having.

But there's more to this bead thing; it isn't long before you hear the chant 'show your tits, show your tits'. Somewhere in the road there's a woman pulling up her T shirt to bare her breasts, and in those brief few seconds a hundred camera flashes go off and she'll find beads raining down on top of her from every angle. There are guys walking the road with their girlfriends sitting on their shoulders flashing their breasts - that extra bit of height helping her to catch the glittering prizes. And it's not just down on the road that breasts are bared; on the balconies there are girls flashing as well. They're easy to find; whenever the road is completely impassable with a throng of men, just look up and there she'll be, trying to catch the beads that are being thrown up to her. There's something oddly sanitised about all this; it all seems to be good wholesome fun rather than something smutty. Partial nudity is pretty much taken for granted in the French Quarter. There are stalls lining the edges of Jackson Square, in front of St. Louis Cathedral, that for a few bucks will paint your face with a bewildering variety of designs. If you're female they can also paint your breasts and upper torso, so you see plenty of women strolling leisurely through the streets that you assume are dressed, but who on closer inspection are in fact not.

Landing in Louis Armstrong airport on the Friday night before Mardi Gras, a stretch limo whisked us into the city where our hosts, the New Orleans-based Southern Comfort, were waiting for us. Barely time to shower and it was off to Arnaud's, a restaurant just off Bourbon Street. New Orleans is famous for Mardi Gras, Creole food, Jazz and Southern Comfort, so on the first night it was only right that we got all four. The meal in Arnaud's was spectacularly good, my main course had me almost weeping with pleasure. It was called 'Sweetbread Sins' and was a large vol au vent filled with sweetbreads, oysters and shrimps, the whole smothered in a red wine reduction sauce. While this culinary Nirvana delighted my palate, a three-piece jazz combo of tenor banjo, double bass and clarinet serenaded us. With the meal over we went across the road to the hotel where Southern Comfort keeps a hospitality suite with a balcony overlooking Bourbon Street. Imagine a hotel suite whose interior space is equally divided between crates of drink, boxes of beads for throwing, and guests. A few moments later, a glass of the golden Comfort in hand, I was on the balcony looking out at a scene of mayhem. The crush of people on Bourbon is astounding, there are so many people thronging that it's almost like a river of humanity, except it doesn't flow in only one direction. Flows, counterflows and eddies ripple before your eyes, the seething throng of revellers and the ever-present beads make an indelible mark on the memory. Multi-coloured beads with a 'Southern Comfort' tag were handed to us to throw and we began to experience Mardi Gras.

Daytime is a deal less frenetic, the roads of the French Quarter are easily walked. Unlike much of America you can get a proper coffee in New Orleans and nowhere better than in the House of Brews on Royal Street. Big soft sofas and comfortable ottomans surround the tables here; chandeliers, beautiful cushions and throws complete the effect. It's elegant and comfortable and the coffee's really good. Royal Street is great for antiques as well; you can find jewels, furniture, paintings and tin toys along its length and just as in a souk, you can haggle for your bargain. Between here and the waterfront is the imposing bulk of the cathedral. It fronts onto Jackson Square, a small park that is kept gated during Mardi Gras. At its edges you can get your palm read, meet a mystic, play a game of chess, get your body painted or watch the street performers, who range from the brilliant to the embarrassingly bad.

Every day I was there, a small band of reborn Christians sang songs of gut-wrenching banality through a powerful PA system. If you were anywhere near the square you could hear them. Actually, come to think of it, you could hear them all over the French Quarter. Small groups of them tirelessly walked the streets with banners urging propriety, less drink and no sex. The best sign I saw read 'Obey Jesus or Perish', which says something for a forgiving god. Some had loudhailers which they used to admonish sinful behaviour. I walked behind a group who used the megaphones to shout 'Whore of Babylon' at any skimpily dressed woman.

It's inevitable that two opposing forces like these, revellers and Christians, were going to face off. I saw a silent version of this played out with banners at the junction of Royal and St. Peter. The Christians had their usual banners like 'Repent your Sins', 'Give up the Devil' and so forth, but standing in a line no more than five metres away was a similar-sized group with placards that read 'So many Christians and not a lion in sight', 'Wash away your sins with alcohol' and 'Pray harder, I'm still in love with the Devil'. I did have a kind of sneaking admiration for the man who spent all of Mardi Gras walking around with an enormous wooden cross on his shoulders. Anyone prepared to give up this much fun in favour of discomfort and ridicule has to be admired in a perverse sort of way.

If you cross Decatur Street from here you can cross the tram-lines and find the levee, the bank that keep the river out of the city, whose highest point is a mere 15 feet above sea-level. Behind the levee are flood walls, as a sort of 'just in case'. Across to the right there's the mammoth span of the 'Mississippi River Bridge' - who thought up a name that original? - and moored not too far away is the 'Natchez', the last remaining river steamboat, resplendent with its bright red paddle wheel at the stern. It sets off twice a day, starting downriver and has a restaurant as well where you can watch the riverside and eat lunch as well.

Down river from here and you're in the French Market, a kind of vast, covered tourist trap. The whole market area stretches all the way to the far edge of the French Quarter and comprises the Farmer's Market and then the Flea Market. The central parts of these are covered, but along their uncovered sides are small stalls, most of which sell beads. In the Farmer's market you can get all the ingredients for Creole food; the spices for Gumbo and Jambalaya, grits, crawfish at $2 a pound, vegetables and fruits in profusion, and chillies. There's an entire display of hot chilli sauces and I went back a second time just to take a note of the names. I kid you not, there was 'Burn in Hell, Osama bin Laden Hot Sauce', 'The Hottest Fuckin' Sauce Ever', 'The Rectum Wrecker', and 'Ass in Antarctica', which came with a drawing of a man quenching his ring of fire in ice. Actually there were more, but they weren't as clever or as understated as these.

The Flea Market sells a lot of beads too - the appetite for beads appears insatiable - as well as carnival masks, costumes and voodoo dolls, but what you notice after a while is that every stall also sells preserved alligator heads, which range from puny little things up to jaws that must have come from creatures well over ten feet long. There must be millions of them in this state. 'Of course there are,' I was told, 'they're farmed. Farmed for their hide and their flesh.' Which led me to tasting a delicious alligator sausage. This was the closest I got to one, although I felt I might have seen one the day we went to the plantation. This was the house whose likeness appears on the Southern Comfort bottle. It used to be owned by Jean Lafitte, a riverboat pilot, smuggler, entrepreneur and sugar cane plantation owner. It's typical of many of the elegant houses along the lower Mississippi and it still retains the slave-master's house alongside. The slave quarters, which housed an inhuman thirty to a room, are now gone and the present owner has put a de-consecrated church on the site. The church, now called 'Spirits', is an excellent restaurant and bar where I got to sample far too much Planter's Punch, a traditional New Orleans drink made with Southern Comfort. Between here and the river I thought a glimpse of gator was possible, but my host Oliver Berney told me that the most likely encounter would be with some of the strange and huge insects that live here. 'Most of them are of the hurty-bitey variety,' he told me.

JUST ANOTHER MANIC LUNDI

There was a last party before the day itself, on what is known here as 'Lundi Gras', or Fat Monday. Playboy Magazine and Southern Comfort were hosting a gathering on Bourbon Street with two playmates of the month and two cyber-playmates, who turned out to be real. When all four girls went onto the balcony and stripped, the noise from the crowd was ear-shattering. This may sound surprising, but after less than an hour at the party I went back to the hotel. There's a limit to how much of this madness a man can take.

Fat Tuesday was a stunner. A clear sky, no wind and a bright sun brought the temperature to over 60 degrees. Strangely, the increasing mayhem seemed to have abated. Instead, the streets were filled with the most extraordinary costumes. Clearly people spend much of the year in preparation and the diversity and the intricacy of the costumes were impressive. We went to see the start of the gay parade, where some truly alarming male genitalia could be glimpsed . One tall, slight man with wings strapped to his back sprinkled some glitter over me as he passed, 'I'm a good fairy, and I bring you good things.' What I liked best were the impromptu parades, where a few costumed people were joined by others, a few at a time, until critical mass was reached. Voila, another parade.

I realised that all week I'd seen no violence, no one aggressively drunk, no beggars, nobody tried to rip me off, and I'd seen no children until today. No doubt parents kept them well away from Bourbon Street. There's no sense of threat in this city, despite the vast amounts of alcohol that are consumed all day long. As well as the full bars, doorways are temporarily converted to sell beer or Hurricanes, and yet there's peace. Even the heavy police presence, which in Europe would in itself spark a riot, here is laid back and calming. No wonder they call this place 'The Big Easy'.

They know how to end things here too. At midnight on Mardi Gras the police line up along Canal Street and from there they sweep across the French Quarter. First come the cars, sirens wailing and lights flashing, driving two abreast. There's no choice, you get onto the pavement. Behind them come the mounted police, riding in phalanx like a flight of geese. Then come the big trucks; the suckers-up, the sweepers and the sprayers. These last make most people leave the pavements for fear of a soaking. And that's it, it goes quiet. Next morning there's not a bead to be seen. Another New Orleans Mardi Gras has come to an end.