Kubla Khan is a sonorous poem, governed more by the dominance of sound and image than the logic of sequential thought.
Coleridge described it as a "psychological curiosity", lines recollected from a drug-induced trance. But does it make much sense? His preface tells how the material world interrupted imagination: he was called away on business and thus could only remember this published fragment.
He speculates at the end of the poem that, could he revive the damsel's song, he "would build that dome in air". That, ironically, is exactly what he has achieved in poetry: created an inspired image of pleasure from "caverns measureless to man".