Castle Walls

I was at Sutro Heights today with some friends, and I thought it kind of resembled a castle wall. I saw this and immediately thought of "Castle Walls" by T.I.

"Everyone thinks that I have it all
but it's so empty living behind these castle walls,
these castle walls...
If i should tumble, if I should fall,
would any one hear me screaming behind these castle walls,
there's no one here at all...
behind these castle walls"

from "Castle Walls" by T.I. ft. Christina Aguilera