I believe nothing can show unity better than music.
Music is an element which can hit any demographic, any where in the world. It is a language in itself and one that creates a bond between everyone who listens to it.
The best place to experience this phenomenon I believe is at festival. you can feel the buzz in the atmosphere, when bands start to play and the waves of voices as the anticipation grows.
When the crowd take over a songs lyrics - it is an awesome spectacle to hear and behold..
Feeling the motion of the crowd - like being within an ocean of humanity where everyone is high on life (and some on other stuff)..
These where taken at the Reading Festival.