Liszt spent nearly seven years on an Italiante opera, Sardanapalo, based on Lord Byron's tragedy of 1821. Working intermittently on the project, he abandoned a continuous draft in 1852.
The surviving music (55 minutes) constitutes the entirety of Act 1 (minus its final cadence). It is given in various degrees of full and shorthand notation. The style is a unique mixture of Italianate pastiche and mid-century harmonic innovation.
Listen to the world premiere recording, and explore the stages of research from silent manuscript to premiere and CD release. More detailed historical research is available in this article for the Journal of the Royal Musical Association.
The manuscript (GSA 60/N4) contains:
Scena ed aria (soprano)
Scena e duetto (soprano and tenor)
a grand Terzetto finale (soprano, tenor and bass-baritone)
The critical edition was published as part of the Neue Liszt Ausgabe in November 2019, and the performing edition for Schott, an orchestration of Liszt's score that draws on the instrumental cues he specified in the manuscript, appeared in Summer 2019.
The next performances take place on:
6, 28 February & 21 March 2020, Weimarhalle, Staatskapelle Weimar
16 April 2020 at Müpa in Budapest (rescheduled for 2022)
Here's a short article for BBC Music Magazine.
Sardanapalo, king of Assyria - tenor
Mirra, Ionian slave, favourite of the king - soprano
Beleso, Chaldian priest and elder statesman - Bass-baritone
Chorus of Concubines - soprano & alto
Eugène Delacroix, The Death of Sardanapalus
(Musée de Louvre, 1827)
Click for a couple of German radio interviews:
And here's an interview in English from 2019.