Many of Facebook's roughly 3, 500 employees joined because they wanted to help shape the Silicon Valley upstart.

WSJ: Facebook's New Millionaires Present Motivational Challenge

You can see the shadow of its perfect conic shape projected on the valley below at the break of dawn.

BBC: Scaling the Ecuadorean Andes

The eastern mountains don't face the entire expanse of dunes, so the wind cuts the Sossusvlei valley into a "U" shape.

CNN: Romancing the dune in Namibia

But by the early 1990s the Blackfoot was in such bad shape--its valley scarred by clear cuts, its tributaries poisoned and turned orange with acid mine runoff--that the movie had to be filmed on rivers to the south.

FORBES: Riverkeeper