I had the opportunity to use a Cray Y-MP 2E at university in the early 90s. At the time there were strict export restrictions, so I had to get a special approval from the U.S. Government (this was in Brazil).

It was a beautiful machine. The C-shaped purple machine was impressive, and the refrigeration system took most the space. And we had some nice SGI Indigo as front-end workstations, so you could optimize your (Forth) code before moving to UNICOS - the Unix flavor used by Cray.

In hindsight, it's ironic to think about all the paranoia and secrecy - for just 666 Megaflops. My not-so-new Core i7 has 150,000+ Mflops, not counting the GPU.