Most achingly-beautiful music

Chopin, Piano Concerto #2, 2nd movement. Keep it going.

Schwartzkopf singing Shubert's Four Last Songs; the blues riff Jimi plays right after Purple Haze on the Woodstock soundtrack; anything by Kate Bush, but especially her earliest works, including "The Man With The Child In His Eyes," "Wuthering Heights," "L'Amor Looks Something Like You".... I share many of the prior choices as well, but what's the point of mentioning yet again Tchaikovsky's Violin Concerto? :-)

Mjm, thanks for mentioning Schubert's Four Last Songs. You reminded me that Richard Strauss's Vier letzte Lieder are also worthy of consideration.

Oooops! Thinking STRAUSS, typing Schubert -- I'm not senile...yet!

Vaughn Williams Tallis Fantasia; second movement of the Barber violin concerto; tie between the final movement of the Mahler Second ("Ressurection") and the Mahler 9th. And how can I leave out the Faure and Duruffle Requiems? There's a lot more of them out there, too, as these posts attest. These are some of my current choices.