Answer:
In Ozymandias by Percy Shelley, there is a type of irony called "situational irony." The situation is the story or poem, in this case. The irony is because Ozymandias is described as powerful, strong, and the "King of Kings" in the beginning. However, his wonderful statue eventually decays and it shows his mortal vulnerability. The irony is that he begins as a grand ruler and ends as a decaying statue of history.
It is a Situational irony, in which that what all left from the Ozymandias is only a broken statue, where before his statue reflects fear but now reflects wonder because of the ruined condition !