From the movie Farinelli, Lascia Ch'io Pianga (Let Me Weep) by Handel, one of my favorite vocal pieces of any genre.
Let me weep for my cruel fate
And sigh after freedom!
And let me sigh
Sigh after freedom!
Let me weep for my cruel fate
And sigh after freedom!
May sorrow, out of pity, break the ropes of my sufferings,
of my sufferings, out of pity.
And let me sigh after freedom!
The voice was digitally created to try to approach the voice of a castrato by combining the voice of a soprano with the voice of a tenor. I happen to absolutely love the created voice, but I doubt this is all that close an approximation of a "castrato" sound.
This is Montserrat Caballe singing it. As always, a breathtakingly beautiful voice in my opinion, but a rather emotionless interpretation, as is often the case with her, in my opinion:
https://www.youtube.com/watch?v=39yb9jUsGm8
Philippe Jaroussky does a better job for my taste:
https://www.youtube.com/watch?v=HWD8d_YL30o