You may remember that catchy OK Go song that had a music video involving treadmills and a dance routine.
Here it is again, in case you've forgotten.
OK Go have made a name for themselves in the interim as having ingenious and highly choreographed music videos.
This, however, has to be their crowning achievement. We'd hazard a guess and say there's at least a thousand extras in it.
We're also pretty sure there's no video trickery in this. Yes, the footage is at a slightly higher speed, but it's all in one take.
Take a look. Also, if you're afraid of heights, don't watch this.