Classical is Cool is one of the coolest things out there.
Canzon primi toni by Giovanni Gabrieli
As one of the first professional symphony orchestras ever Copenhagen Phil (Sjællands Symfoniorkester) did a flash mob at Copenhagen Central Station on May 2nd 2011 playing Ravel's Bolero. Conductor is Jesper Nordin.
In April 2012 Copenhagen Phil (Sjællands Symfoniorkester) surprised the passengers in the Copenhagen Metro by playing Griegs Peer Gynt. The flash mob was created in collaboration with Radio Klassisk http://radioklassisk.dk/. All music was performed and recorded in the metro.