Costentin Cornomorus wrote at 2003-12-27 09:36:33 (-0800)
 > Well, plenty of Westerners thought impressively
 > large American and Egyptian monuments were
 > "primitive". You don't have to be terribly
 > advanced to find your fellowman primitive! You
 > just have to have an attitude of superiority.

Did they?  I don't think that's been the prevailing attitude,
historically.  The Pyramid of Cheops is one of the the Seven Wonders
of the World, and there's a long tradition of attributing mystical
wisdom to ancient Egypt.  Of course, they often looked down on their
Egyptian contemporaries.  Similarly, the widespread refusal to accept
that Mesoamerican monuments could have been built by the ancestors of
the "primative" people living nearby, and theories that they had been
produced by an offshoot of some old-world civilization (or more
recently by aliens).

 > > Besides, wouldn't being bombed back into the
 > > dark ages give them a
 > > certain amount of practical experience with
 > > radioactivity?
 > Certainly could. But if they forget what
 > radiation actually is, all the warnings in the
 > world will not be good enough - neither written
 > nor impressive architecture.

As long as they're aware of the concept of an invisible force that
causes sickness and death which emanates from certain places and
materials, then they can in principle be made to understand that
that's what they're being warned away from.  They don't necessarily
need to understand the physical processes involved.

 > By the way, is there a picture of this monument
 > somewhere? Twould be interesting to see what it
 > looks like.

I think there are some sketches in the pdf I linked to.  I'm not sure
if they actually came up with any final design - I haven't had a
chance to reread it.  Obviously it's not a trivial matter to produce
something like this.