Mark Zuckerberg himself took to Facebook to show off the platform’s enormous data center in Sweden. Located deep in the forests of the northern part of the country in Luleå, the massive facility is noteworthy for the way in which “it uses a variety of local natural resources to increase efficiency and save power.” Since the tiny town is less than 70 miles from the Arctic Circle, the temperature in the area is usually less than 50 degrees Fahrenheit — a fact that proves indispensable in the maintenance of the center’s servers. By using large fans powered by the dozen or so hydro-electric plants along the local rivers, Facebook’s center is able to bathe its six football fields-worth of servers — an area so big that engineers move around on scooters — in the cold air from the outside, thus using about 40% less power than traditional data centers. In the dead of winter, the process can even be reversed, using the heat from the tens of thousands of servers to warm the building. And thanks to its efficient design, Luleå’s drives can be repaired in under two minutes (compared to an hour for a more prototypical design) while only a single technician is needed for every 25,000 servers.