He has collaborated with celebrated conductors Claudio Abbado, Zubin Mehta, Carlos Kleiber, Daniele Gatti and John Eliot Gardiner,[1][2] and worked with opera icons Placido Domingo, Leo Nucci, Ferruccio Furlanetto, Mariella Devia, Marcelo Álvarez, Daniela Dessì, Simon Keenlyside, Bryn Terfel, Ekaterina Semenchuck, and close friend Andrea Bocelli.

His father, Adolfo Mariani, aspired to be an opera singer and studied voice with lyric tenor Alessandro Bonci, a contemporary of Enrico Caruso.

[5] At Harvard’s Loeb Theater, Mariani directed the production of George Bernard Shaw's Candida[6] and was the first director to stage an opera, Vincenzo Bellini’s I Capuleti e i Montecchi.

Through the 90s and onward, he forged a close working relationship with Claudio Abbado (Don Giovanni) and Zubin Mehta (La Forza del Destino, Aida, Nozze di Figaro).

Mariani also undertook prestigious international projects during this time, organizing tours for the Massimo to Japan (Otsu and Tokyo) in 2007 and Finland (Savonlinna) in 2009.

In addition, he brought co-productions from theaters across the world, including San Francisco, Bruxelles, Barcelona, Santiago del Cile, English National Opera, staged by artists such as Graham Vick, Damiano Michieletto, Terry Gilliam, Laurent Pelly and Calixto Bieito.

Mariani’s pioneer program for children, teens, and young adults established the Massimo as a model for other Italian Opera Houses to develop new audiences.

The theater’s fourth Abbiati prize during Mariani’s tenure was for Graham Vick’s production of Wagner’s Der Ring des Nibelungen.

His production of Il Trovatore, staged at the Circo Massimo in Rome and conducted by Daniele Gatti, was revived at Teatro La Fenice and in Bilbao, Spain.

In 2002 Mariani volunteered to teach at the Kodaikanal International School in Tamil Nadu, India, giving classes in literature, music and theater.