About 400 couples to Buenos Aires from all over the world to compete in the World Tango Championships.
More than 350,000 people gather to watch and each winning couple gets a 20,000 peso prize (about $4,800).
The annual festival began on Tuesday and runs through the end of the month.
Tango was born in the 19th-century ports of Buenos Aires, danced by prostitutes and dock workers, reports Reuters.
It reached its heyday in the 1940s with big traditional orchestras, before fading in popularity. But for years after, it was seen as a dance for old people.
In recent years, however, there's been a rebirth in tango among young Argentines. (Watch a video.)
The modern incarnation has moved away from purist rhythms and electronic fusions, reports Reuters, and toward compositions with contemporary themes that speak to a cruder, more complex reality.
Photos by: Raul Arboleda/AFP/Getty Images; Juan Mabromata/AFP/Getty Images; Gianluigi Guercia/AFP/Getty Images; Alejandro Pagni/AFP/Getty Images; Panta Astiazaran/AFP/Getty Images
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