There are a surprising number of rock songs that were directly influenced by classical music. Eduardo di Capua was born in Naples in 1865, and composed "O Sole Mio" (with words by Giovanni Capurro). It's incredibly famous, and very likely you will hum along to the music.
And now to the King of Rock 'n Roll, Elvis Presley. The similarities with Elvis' 1960 #1 hit "It's Now Or Never" are obvious. Actually, the song was explicitly based on O Sole Mio, and nobody every said otherwise.
In the coming weeks we will explore other rock songs that were based on classical music.
UPDATE 27 August 2017 16:55: Sir Christopher Lee sings these songs.