When I was in college, there was a decommissioned synchrotron in the building adjacent to my dorm. I'm not sure when it was last active; my guess would be the 60s or so, well before my time there. The story I heard was that it was deactivated after someone noticed that the windows in the dorm were blackening from stray radiation.
When they shut it down they left the shielding, a big pile of lead bricks, in the garage-like room where the sync lab was operated. For some reason, the bricks, stamped with "Sync Lab" on each one, were still there when I attended, and due to events too strange to explain here, during a Ditch Day I acquired a couple of them.
I kept them with me for some 20+ years, using them as bookends, doorstops, and the like, until I got divorced and left them behind with the ex.
I never had them checked to see if they were radioactive, and I have wondered if they did me any damage over the years. I seem to be ok now, with no noticeable brain damage or anything else. I guess I got lucky. Of course, listening to pirate radio has probably done me more damage than any synchrotron radiation could have.