Facebook builds a park of server near Arctic Circle

It might not seem the obvious location for a new facility to help run the world's second most popular website: a morning's drive from the Arctic Circle and 900km from the nearest capital city. But yesterday, after months of rumours, Facebook announced it would be building three colossal data centres in the town of Lulea, Sweden, to cope with the relentless online activity of its 800 million users.

It will be the biggest facility of its kind in Europe (the size of 11 football fields) and construction is due to start immediately. The contract, worth some $121m (£75m), is a piffling sum of money for Facebook, but it's a big deal for the town. "This is huge," said Matz Engman, head of the Lulea Business Agency. "Really huge."

The reason for locating a data centre in an area that revels in sub-zero temperatures for half the year is immediately apparent to anyone visiting such a facility. Racks of servers pump out an extraordinary amount of heat, and a huge amount of power is needed to keep air temperatures down to around 20C; if it gets much hotter the chances of computer malfunction increase substantially.