What I said about experience might ring in here though. I have always said (and heard others say):
It's easier to find an anime for a song than it is to find a song for an anime.
In other words, being inspired ususally comes from hearing a song and feeling it fits or click with an anime, either for it's style, emotion, interpretation or...so forth. It's harder to do it the other way...seeing an anime and trying to make a video from there..(view Failed Experiments in Video Editing
I saw your other thread and the anime you have in mind.
What I advise is to not let someone else pick a song for you. For me, it's a much stronger desire and urge to work on something I felt myself. More inspiring and makes the whole process easier.
So, listen to some songs you like or at least have and feel it all out. See if anything fits with Metropolis in a way you feel you would like to express it. I find this method becomes invasive though...eventually, you will not be able to listen to a song without trying to mentally match it up with an idea