Nesika, you are right:
Ben Molar - a famous argentinian musician - proposed the creation of the 'Día Nacional del Tango', celebrated all over the world every 11 of december, because that date was the birthday of the creators of two areas of tango:
"La Voz" -the voice- (Carlos Gardel, el zorzal criollo, ídol y representative figure of the tango, born 11 december of 1890) y
"La Música" -the music- (Julio De Caro, great orchestra director and who renewed the tango, born 11 of december of 1899).