On the subject of mighty works fading with time, an expression of it even neater than Ozymandias -
(Not sure who wrote it)
The sword of Charlemagne
of the mighty thrust,
Is now ferrous oxide,
known as rust.
....or, for the absolute ultimate on that theme:
E=MC2 by Rosser Reeves
Some day, perhaps, some alien eye or eyes,
Blood red in cold and polished horny lids,
Set in a chitinous face
Will sweep the arch of some dark, distant sky
And see a nova flare,
A flick of light, no more.
A pinpoint on a photographic plate,
A foot-note in an alien chart of stars
Forgotten soon on miles of dusty shelves
Where alien beetles feed.
A meal for worms,
To mark the curious end of restless man,
Who for a second of galactic time
Floated upon a speck of cosmic dust
Around a minor sun.