You don't have to post a big list all at once. Just add some favorite tunes/pieces whenever you think of them.
Available on Youtube, “Glorious Beer” is a fun drinking song by Dan W. Quinn. He was very successful in the 1890’s, as his voice worked well within the limited frequency range of the brown wax cylinder era.
Arnold Schoenberg - Zwei Gesange, Op. 1 (1898) Here's a link to the score: 2 Gesänge, Op.1 (Schoenberg, Arnold) - IMSLP: Free Sheet Music PDF Download
Claude Debussy , arguably the composer most influential to all 2Oth-century popular music, though certainly not the only influential composer. Hugely influential to modern jazz from 194O on.
Gustav Mahler - Symphony No. 3 (1894-96), here in a performance by the Lucerne Festival Orchestra with Claudio Abbado conducting:
Tchaikovsky's 6th (and last) Symphony, The Pathetique from 1893. My aunt give me an LP when I was in junior high back in the 1950s and it was maybe the first classical recording I fell in love with.