On the coast of northern Sweden, a giant building full of servers, hard drives and wires hums constantly – and is letting you tag photos of your friends on Facebook.
Facebook's enormous data center is located in Luleå, Sweden, which is along the edge of the Arctic Circle and is "surrounded by dense forests and icy river," Mark Zuckerberg wrote on Facebook.
He just recently shared photos from inside the behemoth, including some explanation about how it works and why. Here's the post:
The climate in Luleå is key to the data center's functioning. During the hottest points of the summer, it generally climbs to about 60 degrees, WeatherSpark says. In the coldest winter days, the average low is 6 degrees.
"The temperature in the area is below 50 degrees most days, so we use large fans to pull in the outside air to naturally cool the thousands of warm servers that line the center’s broad hallways," Zuckerberg wrote.
But in the winter they change it and let the heat generated from all the servers keep the building warm.
In all, the main hall is the size of about six football fields, and workers use scooters to get around. The center went live in June of 2013, and about 150 people work there.
Also, as is pointed out multiple times in the photo gallery, old hard drives are crushed and mangled to protect privacy.
The Guardian has a big write-up from last year about the data center, if you want more information.