Simile poems are based on the analogy of the simile. This is one of the oldest forms of literary usage, which creates the subject in a different form for the purposes of the poem. The simile poem is very common in romantic poems, because it allows very strong use of positive analogies and concepts. An extended simile which describes a city as a sewer, for example, will use the sewer analogy throughout.
Examples of Simile Poem:
O My Luve's like a red, red rose,
That's newly sprung in June;
O My Luve's like the melodie
That's sweetly played in tune.