This poem describes Xanadu, the palace of Kubla Khan, a Mongol emperor and the grandson of Genghis Khan. The poem's speaker starts by describing the setting of Emperor's palace, which he calls a "pleasure dome." He tells us about a river that runs across the land and then flows through some underground caves and into the sea. He also tells us about the fertile land that surrounds the palace. The nearby area is covered in streams, sweet-smelling trees, and beautiful forests.
Then the speaker gets excited about the river again and tells us about the canyon through which it flows. He makes it into a spooky, haunted place, where you might find a "woman wailing for her demon lover." He describes how the river leaps and smashes through the canyon, first exploding up into a noisy fountain and then finally sinking down and flowing through those underground caves into the ocean far away.
The speaker then goes on to describe Kubla Khan himself, who is listening to this noisy river and thinking about war. All of a sudden, the speaker moves away from this landscape and tells us about another vision he had, where he saw a woman playing an instrument and singing. The memory of her song fills him with longing, and he imagines himself singing his own song, using it to create a vision of Xanadu.
Toward the end, the poem becomes more personal and mysterious, as the speaker describes past visions he has had. This brings him to a final image of a terrifying figure with flashing eyes. This person, Kubla Khan, is a powerful being who seems almost godlike: "For he on honey-dew hath fed/And drunk the milk of paradise" (53-54).