"Because" by The Beatles was inspired by Beethoven's "Moonlight Sonata" ... BACKWARDS.
I was lying on the sofa in our house, listening to Yoko play Beethoven's "Moonlight Sonata" on the piano. Suddenly, I said, "Can you play those chords backward?" She did, and I wrote "Because" around them. The song sounds like "Moonlight Sonata," too.
One common misconception is that the song is literally "Moonlight Sonata" played backwards. This is not the case. Simply put, the song was inspired by playing the chords of "Moonlight Sonata" backwards (though if you went through the whole song, it doesn't strictly follow the reverse of Moonlight Sonata's chords.)
Listen for yourself! They do sound really similar. (Because, Moonlight Sonata)
Here's Moonlight Sonata ACTUALLY reversed. It sounds kind of creepy...