The CLUMEQ project is designing a supercomputer, and has several sites already built. One of these, a site in Quebec, was built in an old silo that used to contain a van de Graaf generator.
An article in the McGill Reporter from several years ago described the supercomputer installation at Montreal.
The new CLUMEQ Collossus (as the Quebec installation is called) was described in an article in Data Center Knowledge. The design has all of the computers (Sun blades) are in a circle with the core being a “hot core” and the cool air being drawn from the rim.