There's a bit more to this story

"Shelley wrote the poem in friendly competition with his friend and fellow poet Horace Smith (1779–1849), who also wrote a sonnet on the same topic with the same title." https://en.wikipedia.org/wiki/Ozymandias

Horace's entry is: https://en.wikipedia.org/wiki/Ozymandias_(Smith)

  In Egypt's sandy silence, all alone,
  Stands a gigantic Leg, which far off throws
  The only shadow that the Desert knows:—
  "I am great OZYMANDIAS," saith the stone,
  "The King of Kings; this mighty City shows
  The wonders of my hand."— The City's gone,—
  Naught but the Leg remaining to disclose
  The site of this forgotten Babylon.

  We wonder — and some Hunter may express
  Wonder like ours, when thro' the wilderness
  Where London stood, holding the Wolf in chace,
  He meets some fragment huge, and stops to guess
  What powerful but unrecorded race
  Once dwelt in that annihilated place

Shelley's is arguably better but I like both.