right on (history dork strikes!)

the point of the song is this:
all great civilizations die and disappear into dust:

a few references:

Ozymandias is the Greek name for the Egyptian pharoah Ramses

Athens and Istanbul both once part of the Roman Empire (Byzantium)

2 ROmes have fallen- the first is obvious, the second is Constantinople; Moscow is considered the 3rd Rome by the Russian Orthodox church.

Laodacia is mentioned in Revelations- a once proud and prosperous city which slid into apostasy.

The lantern in the steeple in New ENgland is the famous warning against the British troops that was placed in the steeple of Trinity Church in Boston.

Philadelphia- another reference to Revelations, but I used it as a double meaning- it's originally a church in (I think) Asia minor; but I'm talking about Philadelphia 1787.

So the point of the whole song is a detatched look at the fact that all civilizations rise and fall.

The tune is pretty dense I guess...