I agree with tripper, go to La Boca for tango on the streets. It's a very unique barrio in BA and a can't miss. The Argentine king of soccer and current national team coach Diego Mardonna is god in that place as he played a significant part of his career for Boca Juniors.
QUOTE(mmbcross @ Oct 15 2009, 04:29 PM)

Go to La Boca, where you can dance tango on the streets with the locals.
For the really traditional pure tango you must go to a "milonga".
Craigs List has some pretty interesting selections.