The massive amounts of data that these centers chew through every day is overwhelming to us mere mortals:
“Facebook, as the second most-visited site in the world after Google, needs a lot of them. The company estimates that its servers process around 2.4 billion pieces of content and 750 terabytes of data every day. In 2012, Facebook reported that its users took up around 7 petabytes of photo storage from one of its data centers every month.”
I definitely recommend taking a read through it. If nothing else, it will give you a new appreciation of what it takes to make something like Facebook.
Google Data Centers
If you want to dig in a bit more into the impressive data centers that are out there, Google also has a pretty decent set of pages walking through their technology:
Explore them at the Google Data Centers site.