This might sound a little more exciting than it really is. As far as we can tell, it just means a big, especially nice palace, with pretty gardens all around it. The dome is a safe, sunny, happy place. In the poem, it stands for all the majesty and the triumph of mankind, since it's the house of an emperor. However, when it is compared to the power and the immensity of nature, it might not seem so big after all.
- Line 1: This is the only time the name of the palace is mentioned. This dream version of Xanadu is an allusion to a real historical place, built as a summer palace in what is now called Inner Mongolia. Marco Polo visited it, starting a legend that filtered all the way down to Samuel Coleridge in England.
- Line 2: Let's talk for a second about this "dome." What are we supposed to see in our heads when Coleridge uses that word? We'd guess that it's not meant to be just a dome hovering in space or an empty shell. The dome is his way of referring to the legendary palace of Xanadu. When you use one feature of a thing to refer to the whole, that's called metonymy.
- Line 31-32: This comes up in a few places, but here the dome is a symbol for the work of mankind, set against the natural world. The "shadow of the dome…on the waves" contrasts a building with the wild, unknowable power of nature - a major theme in this poem.