See Naples and die, runs the old saying. What was once an exhortation to witness the beauty of a city sat in Vesuvius's shadow could now be interpreted – if some of the wilder media reports are believed – as a direct threat to visiting football supporters.
It is impossible to go to Naples without being warned about the pickpockets, the grime and the menace of organised crime in the form of the Camorra.
Any time spent there will disprove most of the clichés, though. It is a city that leaves an indelible mark on the visitor. One cliché at least is accurate: this is a city whose heart beats football and whose blood runs sky-blue. For many Neapolitans, Società Sportiva Calcio Napoli is everything.
The generation of Edinson Cavani, Marek Hamsik and Ezequiel Lavezzi has now brought hope to a sleeping giant that has suffered appalling mismanagement on and off the field, relegation and bankruptcy in the past decade.
The reported violence in recent games against Liverpool and Manchester City is almost unheard of in Serie A nowadays, but it was a different story over a decade ago. Arriving in Naples as a foreign student on the Erasmus programme, I found optimism for the 2000-01 season was running high.
The team had returned to the top flight three years after being relegated with a dismal return of just 14 points from 34 games. A new owner had taken over, an experienced coach in Zdenek Zeman came in and there was a vast outlay on new players who would cement their position in Serie A.
However, it was a season that proved to be defining for all the wrong reasons, from appalling performances to appalling violence. It was not just in Naples – an Internazionale fan threw a Molotov cocktail against his own team's bus. That Serie A season prompted hand- wringing in parliament, complaints from police that the stadiums were out of control and articles bemoaning the racism, hooliganism and corruption of a once-great league.
In Napoli, no team could have lived up to the hype in a city where – according to one taxi driver – 80 per cent of the population were regular followers, and an eight-day city-wide holiday was declared after the first title was won in the 1980s. That team surely could not.
A club that had once boasted Dino Zoff, Maradona, Careca, Gianfranco Zola and Fabio Cannavaro was putting its faith at the start of the new millennium in the Swiss international David Sesa, Luis Vidigal and Claudio Husain.
The optimism had begun to waver by the time I made it to the 60,000-seater San Paolo. Napoli were rock-bottom of the table after games against Juventus and Inter but, with the visit of Bologna, the fans were looking for a win to kick-start their season.
The stadium was a crumbling coliseum that spoke of former glories and contemporary decay. The pre-match drug of choice was caffeine rather than alcohol as fans flooded the nearby cafes. If the rest of Italy loves its coffee, Naples is a city obsessed, claiming there is something in the water that marks its espressi out.
My flatmate and I negotiated the chaos outside, found our season-ticket seats in the Distinti section, and took our places on the halfway line. It quickly became clear that the action was behind the goal in the two Curva sections, A and B. The stadium had been draped with banners, vast flags unfurled and the noise was thunderous.
Despite being a long-term season-ticket holder for Napoli's opponents tonight, Chelsea, nothing had prepared me for the Napoli faithful. The stadium was as close to a gladiatorial arena as football gets. Fences keep the baying fans at safe remove and, just in case, there's a moat as well.
Flares fizzed and burned all around. The sky-blue smoke enveloped the crowd and, by the time it had cleared, Napoli were trailing. The football was appalling, with only the home goalkeeper livening the proceedings with an own goal and an assist, rocketing it in off a defender's backside as Napoli went down 5-1.
Most of the Napoli action came from the stands. The steady stream of plastic bottles and coins that had been raining down on to the pitch in the first half intensified in the second. The whistles, spitting and obscene gestures erupted into violence at the final whistle.
Suddenly, fans at the other end of the stadium scattered as riot police came in after them. Those around us began to rip the chairs from their iron brackets and hurl them at the pitch. The scene was a 21st-century apocalypse: police helicopters circled against the pink skies of the autumn evening, flames rained down as fans lit sheets of newspaper and sent them towards the pitch while others stood defiantly sparking red flares in each hand. It later emerged that 10 policemen had been injured, and seven fans were in the cells as the media started what would become a season-long debate about hooliganism. The police would later describe the experience to a judge as "going into war".
The thing is, Naples is an extraordinary mix of chaos, contradiction and natural beauty, of dirt and exuberance; a city where people will "steal the socks out of your shoes"( according to northern Italians) but who, once you get to know them, are the most loyal people on earth. The following home game was against Vicenza. Taking the metro to the game, my flatmate and I were beckoned over by a group who were clearly Ultras, the hardcore support whose battle cry includes the line: "Ultras will always search for trouble/And an ideal that never dies."
The opening gambit started the sweat running down my neck. "We saw you last week and thought you were a Bologna fan," the leader said. "We were watching you."
But what about my Napoli scarf? The hat? "We thought you had come in disguise to cause trouble," came the reply. This apparently was a tactic used among the more mentally unhinged section of Italian support. "Now we know you really are with Napoli, it's OK," the leader said, before offering us a lump of hash as if to seal our new-found friendship. They did not care I was English, as long as I also had the Neapolitan spirit.
And make no mistake, it is a spirit. Most of the top-flight Italian clubs have a variation of the Ultras who model themselves on English hooligans of yesteryear. The Napoli version were particularly feared.
They made headlines in Britain for stabbing Liverpool fans in 2010 and last year they put six Bayern Munich fans in hospital. But a Neapolitan friend told me this month. "There hasn't been real trouble with the Ultras for years. They used to cause real problems, but now it's so isolated you never read about it."
In Naples most of the members would call themselves scugnizzi. Probably the closest translation is "lads", replete with their machismo banter, confrontation and the bizarre practice of getting girls' attention by hissing at them.
It was once said that three things summed up Naples' beauty: its bay, Vesuvius and Maradona. While the patron saint of the city is San Gennaro, a Christian martyr whose blood is still supposedly brought out for religious ceremonies, a case has been made for the Argentine to replace him.
Maradona joined in 1984 for a then world-record fee of £6.9m from Barcelona. He led the team to its only two titles, and a Uefa Cup before he was banned in 1990 for cocaine use. Pictures of the legendary No 10 in his pomp were plastered across the city and in most of the houses and bars I visited.
Napoli gambled on another South American to save their season in 2000. That punt on Edmundo spectacularly failed to pay off as the Brazil striker, on exorbitant wages, scored just four times.
The vast investment in what turned out to be average players would send Napoli into bankruptcy three years later with debts of €70m. The club, set up in 1904, collapsed and was refounded as Napoli Soccer. It rejoined the league in Serie C1 and, showing the passion of the fans, broke divisional records for attendance, with gates as high as 51,000. After successive promotions, the club was in Serie A in 2007, finishing eighth.
In 2001, though, there were only a few highs: beating Internazionale at home with 10 men, and putting six past Reggina. A low point was the game that had to be played behind closed doors after fans launched a firework that went off just feet from an opposition player.
The last home game of that tumultuous season was against Roma, dubbed the Derby of the Sun. The equation was simple: Roma win, and the title was theirs, Napoli lose and they were down.
Napoli were not about to go down without a fight, and nor were the supporters. The Roma fans were penned in, fences on both sides and a net above, but the locals threw flares that would burn through the net and cause mayhem as they dropped on to their rivals.
Then panic, as Napoli fans broke into the away enclosure for a brawl, prompting the riot police to douse both with tear gas. Over on the other side we started to rub our eyes, as the gas drifted.
The result? The team fought the champions-elect to a draw, but it proved in vain: they were relegated a week later. There is, as they say, history here.
Nick Clark is The Independent's arts correspondent