The first thing you notice in Mexico City are the colours. Row upon row of grey urban buildings in this enormous city and then, out of nowhere, there might be a concrete house as pink as a blancmange.
But in Coyoacán, south of the centre, the colour is predominantly blue. It was here, in this quiet and affluent neighbourhood named 'the place of the coyotes', that painter and feminist icon Frida Kahlo, better known perhaps for her extraordinary life than for her work, lived and died.
In the Blue House, she entertained friends and lovers including Leon Trotsky, photographer Tina Modotti and surrealist writer André Breton. Now the Frida Kahlo Museum, the house is firmly on the tourist map and small groups of fans ogle at the sight of her sickbed with the mirror above - not for kinky sex sessions but as an aid to the tortured self-portraits that dominated her work. At the foot of the bed are pictures of Communist heroes - Marx, Lenin, Mao - and next door, in the studio, her wheelchair in front of an unfinished portrait of Stalin.
Like many visitors to the city, I am on the Kahlo trail, following a circuit that takes in some of the most interesting sites this sprawling megalopolis has to offer and looking at the remnants of a life that has inspired fans worldwide (notably Madonna), artists, writers and now a feature film starring Salma Hayek. We have a couple of things in common, Frida and I: a life-long obsession with art and problematic facial hair - although, being more unconventional than me, Kahlo made a feature of hers. As a result, her image is instantly recognisable, not just in her own work but in the murals of her more famous husband, Diego Rivera. At the Palacio Nacional, in the historical centre of the city, it is easy to spot Frida and her sister Cristina in his lavish pictorial history of Mexican civilisation from the Aztecs to the Revolution of 1910.
You could do the Kahlo trail in a couple of days, but with its world-class museums, historical sites and thriving contemporary art scene, Mexico City is a place to linger.
Stories about choking smog and violent robbery can put you off. According to my guide book, tales from friends and the Foreign Office website, as a tourist I am probably going to be a victim of crime. If I am lucky, I will be mugged. If not, all manner of horrors - including being kidnapped by my taxi driver, relieved of my credit card and pin number and driven to the nearest cashpoint - await me. The advice: do not look rich, do not look lost and do not look foreign.
In an attempt to curb crime, an elite squad of English-speaking police officers has been posted around the city's major tourist attractions. And Mexico City's secret weapon against crime and police corruption is New York's former mayor Rudolph Giuliani, hired as a consultant, whose zero-tolerance policy cut crime in the Big Apple by 60 per cent. As for the smog, recent initiatives to cut pollution have improved air quality to such an extent that, on a good day, you may not even notice any fumes, especially in spring when wind from the surrounding mountains brings fresh air and keeps temperatures around a pleasant 25C.
On windswept Plaza Garibaldi, mariachi musicians dressed in black suits stand alone in the sun waiting for passing trade. A few blocks away, in the Palacio de Bellas Artes, more Rivera murals vie for attention with a magnificent retrospective of Mexican architect Luis Barragan. 'He took the colour and essence of the small towns and used it in his buildings,' architect and musician Rene Torres tells me later over a drink. We are in Cinnabar, a stylish bar in the district of Condesa, the Notting Hill of Mexico City. I tell him I am staying in the Habita, a discreet but friendly temple to minimalism, and he seems impressed. The night before I had dinner at Cafe La Gloria, a cool little restaurant whose candlelit tables spill on to the pavement. Tonight I have arrived on my own, but, soon enough, Carlos the skateboarding barman is mixing me the house cocktail and I get chatting with my neighbours.
Rene's friend Leonel Fernandez, a film director, has recently returned from New York and finds Mexico City noticeably more affluent and upbeat than it was four years ago when he left. He is full of enthusiasm for the contemporary art scene. The problem with the new film, Frida, he says, is that it has sacrificed historical accuracy on the altar of Hollywood fantasy.
The next day, at the house-cum-studio that Kahlo and Rivera shared in San Angel, west of Coyoacan, a striking avant-garde 1930s building painted orange and blue and surrounded by a fence of tall cacti, I pick up the trail. In his own estimation, Rivera was as ugly as a frog. He kept dozens of ceramic amphibians as if to declare publicly that he was no prince but, despite his ample weight and bulging eyes, he was quite a hit with the ladies.
Light floods into his studio, illuminating shelves of pigment, dangling papier mché skeletons - part of Rivera's collection of Judas figures - and nude images of the artist's models, some of whom became his lovers.
From the roof terrace you can see the San Angel Inn, an old Carmelite monastery that has been converted into a smart restaurant surrounded by small terraces and fountains. The restaurant boasts a bizarre list of famous guests from George Gershwin to Muhammad Ali and 'Prince Philip of England'. As I wander around the shady gardens, a wedding party arrives.
Frida and Diego had just returned to Mexico from New York when they lived in the San Angel house, where they had separate living quarters. Their marriage was falling apart and among various extramarital affairs was a brief encounter between Kahlo and Trotsky.
The Russian revolutionary's old house is just round the corner from Frida's in Coyoacán, surrounded by a very high wall with a watchtower and separate quarters for six armed guards. The need for security was paramount, but ultimately futile. Trotsky lived in this house for a year. It has now been opened to the public as the Trotsky Museum and you can still see some of his personal effects - a pair of glasses, tins of Twinings tea, a faded copy of Pravda - as well as the bullet holes in the door from the first attempt on his life. The final, fatal attack was savage: an ice pick in the head. But the legend lives on in the museum, a song by the Stranglers and various photographs in Kahlo's collection.
Had Trotsky been around in Aztec Mexico, his death would have been even more gruesome. At Templo Mayor, in the heart of Mexico City, are the ruins of the Aztecs' bloody empire, with the remains of its ceremonial pyramid where victims of countless sacrifices had their hearts torn out and offered up to the gods.
Further evidence of pre-Hispanic life and death can be found at the Anthropology Museum, although some pieces are on loan to the Royal Academy's Aztecs exhibition in London. Only 30 miles north is the spectacular site of Teotihuacán. It is an easy day trip and walking around the pyramids, temples and ancient murals you get a sense of the vastness of the Aztecs' monumental cities.
Back in town, we are driving down Avenida Insurgentes. According to my guide Leo, at almost 22 miles from beginning to end, this is Mexico City's longest road. We pass shops, malls and a large pawn shop where you can swap your car for instant cash. The traffic is quite heavy, but not as bad as I had imagined. Green VW Beetle taxis hurtle by and fire-eaters entertain the queues of cars.
A convoy of glittering trucks trundles south, returning from a pilgrimage to the Basilica de Nuestra Señora de Guadalupe. Some worshippers will have travelled the last part of the journey on their knees.
With the minimum wage at around $4 a day, it is no wonder they put their faith in the church. Even Mexico's president, Vicente Fox, once an executive at Coca-Cola, has another job on the side.
Leo says next time Fox's wife might pick up the reins of power. I think Frida would approve.
Factfile
Debbie Lawson travelled with Journey Latin America (020 8747 8315).
A five-night trip to Mexico City costs from £1,245 per person, including flights with British Airways, airport transfers, five nights at the four-star Habita hotel, plus a guided city tour and an excursion to the pyramids at Teotihuacán (price based on two people sharing).
