Inception

 " It's the chance to build cathedrals, entire cities, things that never existed, things that couldn't exist in the real world..."

"In a dream you can cheat Architecture into impossible shapes."

Ariadne Learns How To Build Dreams.

Inception City Explosion - Waking Up From A Dream Scene

Paradox Architecture - Penrose Steps - The Infinite Staircase

" You're waiting for a train, a train that will take you far away. You know where you hope this train will take you. But you can't know for sure. But it doesn't matter - How can it not matter? "

 -Mal's riddle     

The most utopian element of the movie is Limbo-"unconstructed dream space." In this lowest level of subconscious dream space, one can create for oneself an ideal world.

 One way in which we could interpret the film is that it describes what is possible and impossible through the dream states themselves.