the Beirut concrete tower with tanks trapped within is truly awesome: still - unsure what it actually says about war (perhaps it says war is embedded within our notions of civilisation, which ultimately makes it a grisly celebration of sorts) and the fact that it sits within a military base, as you say, notjim, tends to skew any interpration towards what I have suggested in brackets.
Back to the WTC: FIN - you said:
I don't think a simple name plate would suffice here as in generations people will not know what it is for and the attack on our way of life that it symbolised.
I understand your sentiment but just as Robbie Williams seems to top polls such as the 100 greatest single of all time, it seems as if general societal events are considered only in the short term.
I'm not promoting a debate here on which atrocity is worse than another, but I would say empires come and go and we shouldn't worry too much about how the future will remember us. The future has rules we don't yet know and the future will decide what 9/11 meant for itself. If anything, a small, factual account and secular tribute to 21st Century life may help whoever's in charge in the future to accurately interpret what the hell happened and what it meant to the world at large.
To quote the great comic book scribe Alan Moore:
See Babylon fall, see Egypt thrive,
'Til Alexander's Greeks arrive,
Then, next, the Romans come to town.
The Wheel turns, we go up, else down.
Yet Empires still bemoan their lot,
As they're churned under and forgot
'Oh Time', they cry,
And fear the new,
But times change,
Whatcha gonna do?