María de Buenos Aires
The surreal plot centers on a prostitute in Buenos Aires, Argentina; the second half takes place after her death. The characters include María (and, after her death, the Shadow of María), a singer of payadas, various members of the Buenos Aires underworld, a poet narrator who is also a goblin-like duende, several marionettes under his control, and a circus of psychoanalysts. Several elements of the libretto suggest parallels between María and Mary, the mother of Jesus (in Spanish, María) or to Jesus himself.
While certainly not in the narrow sense an opera ballet, because the dance is tango rather than classical ballet, it falls within the tradition of having set dance pieces integral to an operatic work.
The music draws on the nuevo tango idiom for which Piazzolla is famous. The original idea for the story was conceived by Piazzolla's then lover, Egle Martin (though she was already married to Eduardo "Lalo" Palacios). The title role was originally conceived for Martin, but while Piazzolla was still composing the operita, he and Martin broke up after he asked her husband for her hand at Christmas in 1967. According to Martin, Piazzolla said to Lalo, "She is music, she can't belong to anybody, no she is music, she is music, and that's me." After their rift a replacement was desperately needed, but Piazzolla soon met folksinger Amelita Baltar at the Buenos Aires nightclub "Nuestro Tiempo", formerly called "676" and once Piazzolla's home base in Argentina. Baltar's identification with the character Maria paired with her beauty and captivating stage presence made her ideal.
The piece is written for at least three vocalists (one of whom, the narrator, speaks rather than singing). For the orchestration Piazzolla augmented his current working quintet: Piazzolla (bandoneón), Antonio Agri (violin), Jamie "El Russo" Gosis (piano), Oscar Lopez Ruiz (guitar) and Kicho Díaz (double bass); with viola, cello, flute, percussion, vibraphone and xylophone, and another guitar. Maria de Buenos Aires has often been performed with dancers as well as the musicians. There are several extant arrangements, including Piazzola's own and one by Pablo Ziegler.
For some years María de Buenos Aires was seldom staged, though increasingly there have been modern productions, some in concert form and often incorporating dance. The opera had its U.S. premiere at Houston Grand Opera in 1991. The United Kingdom premiere took place on 2 June 2000 as part of the BOC Covent Garden Festival at the Peacock Theatre, London. A semi-staged performance at the Grand Thermae Villa in Rome in 2003 was recorded and has been released on DVD by Kultur Video.
Other recent productions include the Norfolk and Norwich Festival in the United Kingdom (2004), the Teatro nacional de S.Joaõ (Porto) and the Opera São Carlos (Lisbon) in Portugal (2006, 2007, toured to Norway, 2007), the Gotham Chamber Opera at Skirball Center, in New York City (2008), Canberra, Australia (National Multicultural Festival, 2008) and the very successful Teatro di Capua production (2008) which has been produced in several theatres including the Hermitage Theatre in St Petersburg, Russia, Moscow (where it received two nominations in the Moscow Festival of the Golden Mask in 2009), and the 2010 Edinburgh Festival.
A new fully staged production by Australian dance company Leigh Warren and Dancers and the State Opera of South Australia opened in Adelaide on 15 October 2010  and performed at the Brisbane Festival in September 2011. A reworked version of this production featured in the Victorian Opera 2013 season in Melbourne, as a collaboration between Leigh Warren and Dancers and the Victorian Opera performed at Melbourne Recital Centre. It was directed once more by Leigh Warren, with conductor James Crabb, and music supervision by Argentinian born pianist Andrea Katz. The production featured Cherie Boogaart as Maria, Nicholas Dinopoulos as the Cantor, Alirio Zavarce as the Narrator, and additionally showcased cameos from tango dancer Andrew Gill, magician James James and contortionist Jacinta Rohan.
The opera was translated to Swedish by Leif Janzon and premiered by the Piteå Chamber Opera on 15 October 2011 at Acusticum in Piteå (Sweden).
A new fully staged production by Vatroslav Lisinski Concert Hall, Zagreb, Croatia, was premiered on 22 October 2011. The performance was directed by Mario Kovač, with The Zagreb Soloists under direction of Miran Vaupotić, and Chamber Choir "Ivan Filipović" under direction of Goran Jerković. Bandoneón was played by Aleksandar Nikolić, the recipient of Ástor Piazzolla Award in 2008. The circus acts were performed by the circus company Circorama. The singers were Sandra Rumolino, Jorge Rodriguez and José Luis Baretto. 
Long Beach Opera in California performed the opera on 29 January and 4 February 2012 at the Warner Grand Theater in San Pedro, CA, in a production created by LBO Artistic Director Andreas Mitisek that set the opera in Buenos Aires after the "Dirty War" of the 70s; Maria and Payador were people who "disappeared"; he survives and as an old man recalls their days together. The production was reviewed in the Los Angeles Times.
Artes de la Rosa Cultural Center for the Arts in Fort Worth, Texas presented Maria de Buenos Aires on 11 May 2012 directed by Adam Adolfo and with Elise Lavallee as choreographer. It was staged at the historic Rose Marine Theater. Starring as Maria, was Grace Neeley making her Artes de laRosa debut. The actress has been seen throughout the North Texas theatre community taking the stage at Circle Theatre:
- "The role requires an epic journey ranging from youthful naïveté, to rambunctious sensuality, to frailty and despair without ever losing a sense of hope. When we found Grace, we knew we had a woman who could not only embody the role, but truly define tango itself" says Director Adam Adolfo. Keith J. Warren sang the lyric tenor role of Maria’s love interest, El Payador, with JP Cano in the role of the Goblin Ghost Storyteller, El Duende.
The Cincinnati Opera staged the piece on 25 and 27 July 2012 with soprano Catalina Cuervo, baritone Luis Alejandro Orozco, and Jairo Cuesta as the narrator. The director was Jose Maria Condemi, and Tony Award winning dancers, Fernanda Ghi and Guillermo Merlo, as well as Bandoneon player Ben Bogart performed. 
The Lexington Philharmonic Orchestra presented Maria on between 1 and 3 February 2013, with mezzo-soprano Solange Merdinian and baritone Luis Orozco. The narrator was Enrique Andrade and the production was directed by John de los Santos. Bandoneon player Ben Bogart also performed.
The ill-omened María, born "one day when God was drunk" in a poor suburb of Buenos Aires, heads to the center of Buenos Aires, where she is seduced by the music of the tango and becomes a streetwalker. Thieves and brothel keepers, gathered at a black mass resolve her death. After her death, she is condemned to a hell which is the city itself: her Shadow, now walks the city. She has returned to virginity, is impregnated by the word of the goblin poet, and—witnessed by three Construction Worker Magi and The Women Who Knead Pasta—gives birth to a Child María, who may be herself.
- Tema de María
- Balada para un organito loco
- Carta a los árboles y las chimeneas
- Contramilonga a la funerala
- Fuga y misterio
- Milonga carrieguera
- Milonga de la anunciación
- Misere canyengue
- Poema valseado
- Aria de los analistas
- Romanza del duende
- Tangata del alba
- Tangus Dei
- Tocata rea
- SCP 2005.
- Julio Nudler,Horacio Ferrer, Todo Tango. Accessed online, 20 March 2007.
- Teatro di Capua website
- State Opera of South Australia website
- Brisbane Festival 2011 website
- Victorian Opera website
- Quantum Theatre website
- Vatroslav Lisinski Concert Hall website (in Croatian) website
- Review in the Los Angeles Times
- Ben Bogart's website
- Cincinnati Opera's website
- Seattle Chamber Players (SCP), "María de Buenos Aires" performance program, 2005
- Zagreb performance of Maria de Buenos Aires
- Entire Operita with Ballet, with Sandra Rumolino as Maria
- Tangus Dei, a video recording. Ensemble: Seattle Chamber Players, soloists: Pablo Zinger (USA), Leonardo Granados, tenor (Venezuela); Alexander Mitenev, bandoneon (Russia)  Russia).
- Maria de Buenos Aires, a video recording. Astorpia Tango Quintet
- Fuga y misterio (Fugue and Mystery), a video recording. Ensemble: Kremerata Baltica, soloists: Gidon Kremer, violin (Latvia); Andrei Pushkarev, vibraphone (  Ukraine).