I've walked round one and chatted to the resident Cray-1 engineer about the machine.
Long ago (1978!) the Science and Engineering Research Council at Daresbury Laboratories near here aqcuired a Cray-1 from (I think) the Met Office to analyse data from (mainly) crystalography experiments on the beamlines of their X-ray synchrotron.
I had just joined a startup electronics firm that did instrumentation work for Daresbury and my first job was to design some custom commmunication hardware so that a bank of about 20 PDP11 16 bit minicomputers could collect data from around the accelerator. They fed it to two Interdata 32 bit superminis which in turn fed an IBM360 mainframe that organised storage and fed a Cray1 supercomputer. Awesome system for its' day but your top-end PC probably has more grunt now than that lot combined!
Daresbury Laboratories had a village hall sized room that was originally the disk farm for the 360 with load of 3030 removable disks for storage. On occasional visits over the years I saw this room empty as drive technology improved until the storage consisted of a single 6' high 19 inch rack of optical drives.