Just watched some video in Youtube, and found that it is quite interesting, so I just share it here.
As you all know, the most busy websites on the Internet, are Google and Facebook.

The videos below, are showing their main data center.
And no, they do not use only 1 data center, they have servers around the world, and the videos below, are only showing their main data center only.

Facebook Data Center
[tube]-DRxqHrPrFw&[/tube]

Google Data Center
[tube]M-3bdWCOSMQ[/tube]