Barcelona Supercomputing Center

What was once a hallowed place of worship known as the Torre Girona is now the home of the Barcelona Supercomputing Center, filling the expansive main hall with banks of futuristic computer equipment under glass. 

Since 2005 the former church has been home to MareNostrum, one of the most powerful supercomputers in Europe that was instrumental in developing modern microchip technology. The giant machine is used to perform the massively complex calculations involved in such fields of research as human genome mapping, astrophysics, and weather prediction. Physically the computer consists of a number of black computing stacks that are all encased in a giant glass box, which itself sits in the romantically-styled main hall of Torre Girona.

Rebuilt after the Spanish Civil War, the Torre Girona is a 19th-century church that sits on the campus of the Polytechnic University of Catalonia. The space was used as a Catholic church until at least 1960, when it was deconsecrated. Since then, it has been used for more functional purposes, finally being inhabited in full by the supercomputer and its attendant offices. 

MareNostrum may not be the most powerful computer in the world any longer, but it will likely remain the most visually appealing for years to come.