"Kubla Khan," by Samuel Taylor Coleridge, is a poem about the summer city of Xanadu (Shangdu). Coleridge was inspired to write the poem after an experience with opium, as well as his reading of Marco Polo's visit to the Emperor Kublai Khan. Because of the limited information about China during that time, the poem uses symbolism to create a venue that likely never existed, and shows a romantic view of the power and scope of the Chinese Empire.
Through wood and dale the sacred river ran,
Then reached the caverns measureless to man,
And sank in tumult to a lifeless ocean:
It was a miracle of rare device,
A sunny pleasure-dome with caves of ice!
(Coleridge, "Kubla Khan," eNotes eText)
The place depicted in the poem is a great, hidden "pleasure-dome," a palace built underground near a river that ran down into "measureless caverns" into a "lifeless ocean." The idea is that Kubla Khan had such power over his citizens and over nature that he decreed this palace built for his own pleasure, not for war or to raise his status among other nations. The poem includes themes of spirituality, mystery, and romance; the hidden city of Xanadu is portrayed as a place where all pleasures are allowed, and which the Western mind cannot fully comprehend. It also serves to enhance the sense of "otherness" of China and related nations, as these were seen as foreign and strange; the poem plays on these prejudices to form strange and unsettling imagery.