Emerging out of the gritty experience of immigrant life, tango’s roots first formed in the mix of cultures living along the edge of the Rio de la Plata. More than a hundred years later, I arrive in contemporary, cosmopolitan Buenos Aires to seek its relics.

In my hotel room, Carlos Gardel croons in a background crackle on the phone. I take this as a positive sign. The infamous singer brought tango into the international spotlight from its original home in brothels and immigrant barrios. Now, Gardel is a bit of a patron saint in Argentina. Black and white portraits of his seductively smiling face hang in store shop windows, are propped in shoe-shiner’s cases, and grin from fridge magnets and postcards. Tragically dead at 38 in 1935, his tomb in tranquil Chacarita cemetery, at the end of the B line, is eternally brightened by flowers and lipstick kisses.

Take eight steps into Buenos Aires, South America’s Paris, and it’s obvious that tango is alive and well. While there are many ways to find it – strolling in the streets, or looking through the widely available city guide "Buenos Aires Tango" – the San Telmo barrio is an excellent beginning for any education in Gardel’s beloved Buenos Aires.

Perhaps the most vibrant site of tango heritage, this neighbourhood was once home to the European immigrant elite before poor families took it over. Today it retains an authentic flavour, a mix of antiques shops, tanguerias, local restaurants and stores. Full of crumbling turn-of-the-century mansions and cheaper and quainter hotels than are found in the Microcentro, San Telmo is a must for anyone seeking the city’s antiquity.

During the Sunday afternoon antique market, Plaza Dorrego, the barrio’s heart, fills with items – and images – from the era when tango was beginning to brew. Tarnished mate bombillas – metal straws for a South American ritualistic tea – rest beside silver mesh purses used by old-time tango dancers while Victrolas emit the scratchy, soothing voice of – who else? – Gardel. At midday two divinely clad dancers launch into tango and pause between performances to explain – in Spanish – its history. Nearby, a man plays bandoneon to accompany other costumed dancers. Beside puppet shows and street performers, artists sell some often incredibly good photographs and vibrant paintings of tango couples.

Here, portenos – citizens of Buenos Aires – do the deed on stage, or by offering lessons advertised in windows or on flyers. I take a free lesson with Nora Mendoza, a teacher and dancer dedicated to the tango. "Maybe coming from outside the country you give the tango more importance than the people here," she says, speaking of her frustration with tango’s loss to rock music and other popular forms. Still, she explains that there is a solid core of artists whose persistence keeps tango alive.

After she guides me through the eight basic steps that are the core of tango, I head for more history at the friendly Museo Vivo del Tango, Piedras 720. Featuring four of tango’s luminaries – Anibal Troilo, Carlos Gardel, Astor Piazzola and Roberto Goyeneche – the museum has an excellent exhibit of 605 photographs and personal artefacts, including one of Gardel’s combs.

My next stop – La Boca – was once an Italian shantytown where brothels hosted the illicit dance. Along the brightly coloured Caminito, beside the oil-stained waters of the old port, no trace of that rougher edge remains but the neighbourhood, behind the tourist polish, is strictly Bohemian. In the artisans market, I’m delighted to see a couple spontaneously tango, laughing and rubbing noses, a long way from the days when male immigrants vastly outnumbered women and romance demanded a mating dance.

The more I look, the more it seems that tango, while a tourist commodity, is also, for many, a part of everyday life. On New Year’s Eve, I mention the word on a rooftop, firecrackers blasting the sky into light, and a couple presses together to dance. "Tango is a people’s way of being," says Alejandro Andrada, an Argentine journalist and filmmaker. "It’s a translation of how Argentines live."

His comment explains why searching for it is a bit like looking for a baguette and a cup of coffee in Paris. It’s everywhere. On the antiquated subway an old man in a rumpled suit plays bandoneon for stray centavos. Near the tango information kiosk at Corrientes and Parana Streets, kids perform on plastic accordions. One night I’m kept awake by the voice of Gardel, like a ghost, singing through a thin wall. But what I’m seeking still seems unattainable – like trying to find Gertrude Stein on today’s Left Bank. What I want is a glimpse of the late 19th century when men danced with men to practice their steps and tango was a risqué activity. Then, women were paid for the act and knives flashed secret glances around shadowed rooms. In those days, tango was obviously, as Andrada explains, "a symbol of rebellion against the economic differences that have always been a force in Argentina."

Café Ideal brings me closer. Tucked two doors in from the corner of Suipacha and Corrientes Steets, it is distinguishable by an old-fashioned iron sign. Built in 1912, the vast upstairs milonga – dance hall – where Madonna filmed the tango scene for Evita, glimmers under a giant disco ball. For a five-peso admission fee, you can bathe in the feel of the authentic, watch the dancers, or even take a lesson. The place closes early – never later than midnight – but nearby is Tortoni’s at Avenida de Mayo 829.

The café that Argentine writers Borges and Julio Cortazar, among others, frequented, Tortoni’s is all dark wood, marble, heavy red curtains and is seeped in aristocratic energy. Tango drifts from the back salon, host to an eleven-dollar show with a dancer in a dress redder, if possible, than the plush curtains.

"At the beginning it was an orgiastic mischief, today it is a way of walking," Borges wrote in 1930. Now, this statement is being reaffirmed. "In Argentina, there is a revaluing of tango at the same time as it is becoming more popular internationally," says Andrada. Francis Ford Coppolla and Robert Duvall are currently filming Assassination Tango, a movie about an agent drawn into tango’s steamy underworld, while President Fernando de la Rua has appealed to UNESCO to designate the dance both a masterpiece of humanity’s heritage, and indisputably Argentine.

The final steps of my pilgrimage take me to Carlos Gardel Station. I walk through the modern space of a mall to Carlos Gardel Street, a nondescript cobblestone lane with a statue, murals and a construction site of what, I cynically assume, will be condominiums. La Recova del Abasto, where Gardel once sang, sits on the corner. Inside, Rafael, the owner, approaches. Smouldering with old-fashioned tango energy, he shows me a book of turn-of-the-century photographs. The mall is, in fact, encased in the original structure of the Abasto mercado where Gardel sang as a boy. The men at the construction site are building a theatre.

Around the corner, the crumbling balcony of Gardel’s childhood home pokes up from behind a wall hiding renovations to make it a museum. Dark eyes peering into mine, Rafael tells me that his bar has live music and dancing on weekend nights and invites me back to tango with him. When I pull myself away, I know I won’t go. With a finger clad in a wedding ring, or at least a date, I would, but Abasto, for me, feels a bit like a time warp where tango could lead me into an historic haze of debauchery. Here, I’ve found it – tango’s authentic edge, its sensuality and intimating darkness, with Rafael.

Returning to the comfort of San Telmo’s charms, I turn the television to Solo Tango, the all-tango-all-the-time station. I’ve glimpsed tango’s modern reflection and gained a sense of the form not as image but heart, not costume but soul. And still, tango hovers like Buenos Aires humidity, and I know there is always more to explore in the city that never sleeps.