The vivid colours of folk art and memories of the struggle for freedom converge at the shrine of a revolutionary icon, the artist Frida Kahlo.

The first thing you notice when you enter the bright shuttered doorway of the Museo Frida Kahlo in Coyoacan, Mexico City, is the women. The museum was given to the Mexican people by Kahlo's husband, the muralist Diego Rivera, shortly after the artist's death in 1954 and the staff are, for the most part, female. There is nothing so striking in that. What is striking is their appearance. Almost without exception the young women who issue your ticket, ensure you do not take photographs and offer you guided tours throughout the house and grounds sport long dark hair drawn severely off their faces, eyebrows cultivated into strong arches that dominate the face, facial hair left untended. Much like the woman whose memory they so proudly serve.

Mexico is a land of icons. Any visitor is likely to return home with some example of the symbolic imagery that is everywhere from flower-strewn depictions of the Madonna to representations in sugar, plaster and tin of the joyfully ghoulish symbols of The Day of the Dead. But today one of Mexico's greatest icons is Frida Kahlo. Her painfully autobiographical art representing the agony and passions of her turbulent life are increasingly sought by international collectors, her fame now eclipsing that of her once far more famous husband.

Yet it is Frida the person that most draws people to Kahlo. The tormented and troubled life of physical pain which left her in a wheelchair and, ultimately, bed-bound, combined with her passion for politics and for Rivera (she loved him so much she married him twice), has created a cult of Frida. Her image can be found everywhere, on posters, mugs and T-shirts. Her influence on young artists, on young women such as those in her museum, is palpable. On a wall in my home is a print by a contemporary Mexican artist, bought by my husband as a memento of our first trip to Mexico some years ago. Surrounded by images of the tiny tin body parts left in churches as tokens of prayer and thanks is the artist's portrait in place of the customary religious image; Frida as goddess or saint. And this is just the start. Now the cult is about to go celluloid: Salma Hayek is starring in the story of the artist's troubled life, on location in Mexico City

The pretty, sleepy suburb of Coyoacan is a six-mile metro ride from the city centre. With its cobbled streets, candy-colour houses, leafy squares and parks it feels infinitely older than much of the rest of the city which has grown up around it, more the old-fashioned Mexico of the visitor's romantic imagination. It is an area notable for its history of left-wing, bohemian and artist residents and it is here that the search to uncover the legend of Frida Kahlo should begin.

The Museo Frida Kahlo, or Casa Azul (Blue House), lies on the corner of Londres and Allende, a few streets from the casual hub of the Plaza Hidalgo, Coyoacan's main square and a 20-minute walk from the metro station. Its cobalt walls were built by the artist's father in 1904. It is a bright, whimsical house bursting at the seams with the rich traces of Mexican folk art in the form of giant papier-maché Judas figures, clay pottery, vivid tiling and small painted retablos giving thanks for miracles great and small

above a cabinet containing one of the colourful Indian costumes Kahlo loved to wear, reads "Aqui nacio Frida Kahlo el dia 7 de julio de 1910" (Frida Kahlo was born here on July 7, 1910"). Kahlo was, indeed, born in this house, lived much of her life, worked and died here, but the year of her birth was 1907, not 1910, the year the Mexican Revolution began. Fiercely proud of the indigenous Mexican people and supporting their struggle for freedom throughout her life, Kahlo wanted the year which marked the rebirth of her country to mark the year of her birth, too.

Evidence of the physical struggle and black-as-treacle humour, so much a part of Kahlo's life and work, is strongly on display. A tiny decorated plaster corset, one of many she was forced to wear in later life, sits on her richly decorated bed, the mirrored canopy which enabled Kahlo to paint her many self-portraits serving as reminder of her physical confinement. In her studio a wheelchair rests at the easel of an unfinished portrait of Stalin to whom she shifted her political sympathies after her intense love affair with Trotsky ended. (Trotsky and his wife fled to Mexico in 1929 and his home a few streets away at 410 Avenida Rio Churubusco is now also a museum, largely untouched since his murder there in 1940.)

Kahlo's death mask is also on display, dramatically enshrouded by a rich floral wreath, while on the patio her ashes are exhibited proudly in a large pre-Columbian urn. Of Kahlo's own works there are relatively few, although pieces by some of the many artists who visited the Blue House, including work by Paul Klee and Yves Tanguy, help appease those seeking a more traditional dose of art fulfilment. Khalo's work is displayed widely throughout the city in galleries such as the Museo de Arte Moderno and most comprehensively at the newly opened Dolores Olmedo Patino Museo. But here, in Kahlo's house, there is a sense that the main point of visiting this museum is to visit the legend and help to keep it alive.

The neighbouring suburb of San Angel, a short cab ride away, is home to one of Mexico's finest crafts markets. On Saturdays the pretty Plaza San Jacinto comes alive with colour as the Bazar Sabido (Saturday market) spills from its official site in one of the houses on the north side of the square onto the tree-lined pavements. Folk art and crafts from all over the country find their way here. Like Coyoacan, San Angel was once a quiet village separated from the rest of Mexico City and, like its neighbour, its sleepy streets offer a refuge from the centre's relentless hum. An affluent location, expensive modern homes stand alongside old colonial houses and it was here, never too far from Casa Azul, that Kahlo and Rivera lived and worked at the end of the 1930s.

The Museo Casa Estudio Diego Rivera y Frida Kahlo honours both artists, at least in name. Two modern houses, pink for Rivera, blue for Kahlo, served as separate studios and homes one linked by a covered bridge. Again the museum is more an intriguing insight into their personal history rather than their art. Their marriage began to crumble and finally Kahlo officially moved back to the house in Coyoacan and the couple briefly divorced before remarrying a year later in 1940. None of Kahlo's works and relatively few of Rivera's are on display, but it is filled with thousands of items from their personal collections of folk art.

High in the mountains of the state of Chiapas, the beautiful hill town of San Cristobal de Las Casas is better known for its history of political unease than its place on the Kahlo trail. Yet its ongoing struggle for the rights of the indigenous Indians is a cause the artist would have probably supported. It is a focal point for political action within the region (earlier this year the Zapatista National Liberation Army led a peaceful convoy from San Cristobal to Mexico City to speak on behalf of the Chiapas Indians).

San Cristobal is one of Mexico's most picturesque towns, filled with the narrow cobbled streets and colourful colonial architecture you would expect. But its setting in the mountains, within a pine-clad valley where the altitude produces an air that is thin and clear and a light that makes the houses appear more pastel than bright, sets it apart, as does the strong presence and history of its various Indian populations. Its market is filled with beautifully woven textiles and leather goods from outlying villages, its churches more appealingly rustic than the gaudy golden cathedrals of larger towns.

Kahlo and Rivera travelled to San Cristobal and become friends with the archaeologist Franz Blom and his wife, the social anthropologist and photographer Gertrude (Trudy). The rambling house where they lived, Na Bolom, is now a museum and charitable foundation dedicated to helping the local Lacandon Indians with whom Trudy worked particularly closely. To visit the museum today is to have a captivating insight into the history of Chiapas. The house is filled with books, archaeological treasures (many of which were uncovered by Franz on his digs) and a wealth of photographs including such legendary figures as the revolutionary Zapata and Kahlo herself.

An oft-quoted line of Kahlo's is the last entry in her journal: "I hope the leaving will be joyful, and I hope never to return." She died of an embolism in bed at the Casa Azul on 2 July, 1954. The entry has led to speculation that the artist took her own life. But Kahlo's last painting, a sensual still-life of watermelon, on show in the Museo Frida Kahlo, bears her other, most public final statement: Viva la vida (Long live life!). Controversial and contradictory even in death, the woman who fought for the spirit of Mexico in her work and in her self has, in her way, come to embody that same spirit. It is this essential Frida who has been raised to the status of icon, in whose image both ancient and modern Mexico have found a voice.