I used to work...
...for Digital, back in the day. But the bit I worked for was the bit that had the support contract for Dell in the UK. So when I showed up on site, it was 'Hi, I'm Mr. Store from Dell'. I mostly worked on servers...
I worked in some interesting places... Special Branch offices, where I first encountered the concept of a server *built in* to a literal safe. Essex police, in multiple police stations fixing troublesome RAIDs. GCHQ, where the contents of my bag was checked before and and after I left site... no big deal, although _no_ hard disks that were replaced ever left the site! Couple of military sites also...
But the most paranoid security I ever encountered was at one of the shadier offices of the BT Research Establishment, at Martlesham Heath. That was the only place I wasn't even allowed *near* the server; I had to wait at reception, and the faulty server was eventually wheeled out to me, on a trolley, and there it was that I fixed it.