Early life and education Born Carlos Felix Cillario in San Rafael, Mendoza, Argentina, he went to Italy with his family in 1923.
His debut as a conductor took place with Il Barbiere di Siviglia in Odessa in 1942, where for a short period of time he also taught violin at the city's conservatory.
During the Second World War he returned to Argentina where he founded and conducted the Symphony Orchestra of the University of Tucuman, and over the years he toured several times in South America, including Buenos Aires and Mexico City.
In 1964 he made his debut at the Royal Opera House in London (Covent Garden), at the express request of Maria Callas, conducting her for a return to the stage in the famous series of 7 performances of Tosca with Tito Gobbi, directed by Franco Zeffirelli, in what would later be considered one of the most celebrated concerts in the career of the "Divine".
The concert represents one of the iconic moments in the history of opera: crowds of people had queued for days to see the singer, who at the end of the first opening night responded with 27 calls to the stage and an ovation that lasted forty minutes.
He then conducted on numerous occasions leading artists in the history of world opera, including Luciano Pavarotti, Renata Tebaldi, Mirella Freni, Joan Sutherland, Renata Scotto, Luigi Alva, Franco Corelli and many others, and collaborated repeatedly with directors such as Luchino Visconti and Franco Zeffirelli From the end of the 1980s, he radically reduced his European commitments, although he still dedicated himself to some collaborations, especially in Sweden and Norway.
In particular, he consolidated an ongoing relationship with the Royal Swedish Opera in Stockholm and with the nearby historic Drottningholm theatre, where each performance included the use of 18th-century costumes, both for singers and musicians.
Cillario established a deep bond with Australia, returning for several years to conduct, but then interrupting the collaboration due to difficulties in coordinating these activities with the international career that had been consolidated in the seventies.
Despite his intense international activity, he always maintained a strong bond with Bologna and the city of Castel San Pietro Terme, where after his retirement he spent the last years of his life dedicating himself to composition and writing.
Among his main works are Variazioni su un tema Egitto and Fantasia e Fuga per quartetto d’archi, and a series of memoirs on the most important artists, musicians and people he met during his career.