Normally supercomputers are housed in high security government buildings which are specifically built and designed to accommodate such mega structures but the MareNostrum in Barcelona Spain the 9th largest supercomputer in the world, fifth fastest in the world and the largest in Europe is installed in a Chapel. The supercomputer consists of 2560 JS21 blade computing nodes, each with 2 dual-core IBM 64-bit PowerPC 970MP processors running at 2.3 GHz for 10240 CPUs in total. It has 20 TB of RAM and 280 TB of external disk storage for more persistent storage. Running on SUSE Linux it is capable of 62.63 teraflops and a peak performance of 94.21 teraflops. It may look beautiful from the top but when you dig deeper it gets more typical.
MareNostrum's Myrinet interconnect fabric requires four cabinets. Myricom did a nice job of reducing the cable count as much as they could by using quad-link ribbon cables between their switch elements. But with 12 separate switch elements in the fabric that means they still have a lot of cables and more cables means more connectors, more points of potential failure. They also use one cable per compute node, as is typically done in cluster configurations. Lots more cables, lots more connectors.

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