Apparently it is a «tango operita» by Astor Piazzolla based on a text by the Argentine poet Horacio Ferrer.
It is sung in Spanish with great passion and played by a vivacious onstage band. The score for Maria de Buenos Aires is passionate and congruent, the production is constantly inventive, engaging and satisfying and all the performances are marvellous. I almost don’t want to give anything about it away at all (or possibly I can’t…), It really has to be experienced first hand.
Go and enjoy. I hope you do.