Of course, there is a lot of classical music to recommend. The following are some classical music works that I think are good:

-Beethoven: "Symphony No. 9", "Moonlight Sonata", "Symphony of Destiny", etc.

-Mozart: "Requiem", "Serenade", "Turkish March", etc.

-Bach: "Unaccompanied Violin Suite No. 1 in G major", "Well-Tempered Piano Collection", etc.

-Chopin: "Nocturne in E flat major", "Army March", etc.