There's been a lot of speculation about the meaning of these lyrics. I know the inspiration for the song is a painting by Mexican artists Frida
Kahlo.

I used to rule the world
Seas would rise when I gave the word
Now in the morning I sleep alone
Sweep the streets I used to own
I used to roll the dice
Feel the fear in my enemies eyes
Listen as the crowd would sing:
"Now the old king is dead, long live the king!"
One minute I held the key
Next the walls were closed on me
And I discovered that my castles stand
Upon pillars of salt, and pillars of sand
I hear Jerusalem bells a ringing
Roman cavalry choirs are singing
Be my mirror, my sword, my shield
My missionaries in a foreign field
For some reason I can't explain
Once you go there was never, never an honest word
That was when I ruled the world
It was the wicked and wild wind
Blew down the doors to let me in
Shattered windows and the sound of drums
People couldn't believe what I'd become
Revolutionaries wait
For my head on a silver plate
Just a puppet on a lonely string (Ooooh)
Ah, who would ever want to be king?
I hear Jerusalem bells a ringing
Roman cavalry choirs are singing
Be my mirror, my sword, and shield
My missionaries in a foreign field
For some reason I can't explain
I know Saint Peter won't call my name
Never an honest word
But that was when I ruled the world
Ooooh Ooooh Ooooh Ooooh Ooooh
(repeat with chorus)
I hear Jerusalem bells a ringing
Roman cavalry choirs are singing
Be my mirror, my sword, my shield
My missionaries in a foreign field
For some reason I can't explain
I know Saint Peter won't call my name
Never an honest word
But that was when I ruled the world
Oooooooh Oooooooh Oooooooh
Coldplay "Viva la Vida"
I guess the words could apply to any powerful entity's fall from grace. Some believe it is about the French revolution or about Louis XVI.
I don't really know what these lyrics are about but all I can think about is G.W. or Cheney sitting on his porch sometime in the future thinking
these very same thoughts.