Ezio is based on a libretto by Pietro Metastasio which was first set to music by Nicola Porpora (1728), then by Georg Friedrich Handel (1732) and Christoph Willibald Gluck in 1750, amongst many others. The Vienna version, premiered at the Burgtheater in Vienna on 26 December 1763 is a completely new arrangement of the original Prague version of 1750. The revival of Italian opera and the upheaval which followed in the wake of the so-called opera reform make the new version a true reform work.
The Vienna version offers more concentrated dramatic material and redresses the dramatic weaknesses of the first version. Thereby the characterisation of the individual roles is clearer and gains in conciseness. The main plot; Massimo's intrigues and the resulting fall of Ezio from celebrated hero to outlawed traitor, together with the love affair between Ezio and Fulvia becomes the focus of attention.