Tango originated in the working class districts of Buenos Aires in the late 19th Century, but it has also conquered what is usually a rather sleepy town in the Arctic north of Finland.
As far as the eye can see, couples dance the tango on the tree-lined street beneath a brilliant cobalt blue sky. It is 02:00 in the morning and the sun has barely dipped below the horizon - and it will soon rise again.
The sound of the accordion fills the warm summer air and the orchestra starts up - the drums, then the violins. The singer bursts into a song called Satumaa, or Fairytale Land.
Finland's most popular and most frequently performed tango song describes a faraway idyllic land where people live happily. But in this sad tune, the land can only be reached through music.
This is Tangokatu, or Tango Street, in Seinajoki - a small town three hours' train ride north of Helsinki. Seinajoki's main street has been renamed especially for the tango festival, which is the highlight of the Finnish tango calendar.
The five-day festival has been going for nearly 30 years and attracts over 100,000 tango-mad Finns. And there are all sorts here. Men in sandals, cut-off denim shorts and cowboy hats. An elderly couple in matching shell suits. Women wearing leopard-print and polka-dot dresses - and there is a lot of leather.
I came to find out why the Finns are so in love with the tango. After all, they are stereotyped as being withdrawn and quiet. Hardly the fiery, Latin-American type.
The tango took Finland by storm in the 1920s and 30s after being exported from Buenos Aires. But it was during the grim conditions of wartime Finland that the Finns made this music their own.
Lyrics of lost love and sorrow struck a chord with those who had lost loved ones during the fighting - and these sad songs, which are nearly always played in a minor key, have remained firmly in the national consciousness ever since.
The Finnish version is slower and simpler - melodies taken from old Finnish and Russian waltzes are weaved throughout. The accordion replaces the Argentine bandoneon.
The dance is also different. No fancy flicks of the legs from the women but the Finns dance closer, bodies pressed firmly together.
Inside a cramped, sweltering sports hall, the tango moves are being closely scrutinised in a dancing competition. A woman with long blonde hair in a crushed, red-velvet dress glides past. A brunette in bright yellow sails the other way.
One couple, Sari and Raine Ristola, have been competing at Seinajoki for 10 years - and the emotions are just as strong for them now as they were the first time they danced here.
Raine cannot put the feeling into words. Instead he rolls up a shirt sleeve to reveal an arm covered in goosebumps. Then Raine's bright blue eyes suddenly light up. "When you are dancing, it is like loving. Well, maybe the bit before. The feeling is so high," he says.
Like Sari and Raine Ristola, most people here are middle-aged. But some younger people can be seen dancing the same steps as their grandparents did before them.
The tango festival culminates in a televised X-Factor-style singing competition inside the cavernous Seinajoki Arena. Six entrants, all in their twenties and thirties, have been voted by text message into today's final. But only one will be crowned as the Tango King or Queen of the year.
This is a major event. Former Kings and Queens have gone on to become big celebrities. Even the Finnish President, Sauli Niinisto, is here tonight.
One singer distinguishes himself by singing a tango version of a popular Finnish pop song. Pekka Mikkola - a music student from the northern town of Oulu - is the latest person to join Finland's only royalty.
"I have already got a big head," Pekka jokes as he struggles to put on the crown. He has every reason to be happy - a record deal, a full national tour and instant fame await him.
On Tangokatu at three in the morning the sun is already beginning to creep up over the horizon. Partners-to-be will soon meet for the first time and share their first tango together. Feet tapping, eyes closing, bodies swaying to the music.
I recall what Arja Koriseva - a former Seinajoki Tango Queen - told me earlier in the day. Her parents got together whilst dancing the tango in a wooden hall, tucked deep in the Finnish forest. Finns may be quiet, she said, but tango gives their feelings a voice.
And on a beautiful night like this, the Finns could be forgiven for thinking they had finally found that distant, magical, fairytale land of Satumaa.
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