This place is not a place of honor.
No highly esteemed deed is commemorated here.
Nothing valued is here.
This place is a message and part of a system of messages.
Pay attention to it!
Sending this message was important to us.
We considered ourselves to be a powerful culture.
That first part sent shivers down my spine for some reason, how would you warn future cultures(that don't speak your language, which may be long forgotten, or misinterpreted) of nuclear waste? Yes, this is very old, but still interesting.
tl;dr version: Language as we know it may not exist in 10000 years, but nuclear waste will, how does one warn someone of a dangerous site when that someone may not even speak your language?
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This would work, I would think.