It occurred to me after seeing this on TV several times this year, that I found myself thinking about caves. It's a TV ad for a paint product (valspar), but every shot looks like an oddly man-made cave. There's a sea cave, a tree cave (?),an ice cave, a Classic TAG pit( ), a desert cave, and a mountain cave.
http://www.youtube.com/watch?v=EL5q2HanzIA
Just thought I'd share. Music is pretty good too.