Shibuya crossing is one of the busiest crossings in the world. When you walk out of Shibuya station you are confronted by huge electronic billboards and screens. Then there are the people. Hundreds cross at this crossing every single time the lights change. Like hordes of marauding barbarians they mass at the lights and when the lights change they charge, or stroll, out either heading for the station or... god knows.
Starbucks has one of the better views overlooking the crossing. Nearly all the videos on the web you'll find have the view from Starbucks.