"Ozymandias" by Percy Bysshe Shelley - Irony

"'My name is Ozymandias, king of kings; Look on my works, ye Mighty, and despair!' Nothing beside remains." That is one of my favorite few lines of all the poems we've read so far. The irony is just splendid! This man was king of a great land. He controlled all that the eye could see and had marked the whole area with his touch. He even made a statue of himself, so that the whole world could see that Ozymandias was the king of kings! Nobody could ever be greater than he! This is proclaimed on the plaque, while the whole area around him is crumbling apart. What is the effect of this irony? I see the irony as the speaker's way of displaying his theme - nothing lasts forever. That's his theme in cliché format. What he really is trying to tell the reader is that what you have in life now will not stay with you in eternity. Eventually, everything will change. If not, then Ozymandias' statue would be amidst a great city.