Well, if our speaker is "sailing to Byzantium," then the title is a big signal that the poem takes place in the middle of a journey. As it turns out, this journey seems to be both literal (the speaker travels from "that country" to Byzantium) and metaphoric. Interested in why the journey becomes a central theme of this poem? Check out what we have to say about it in "Themes."
Come to think of it, the title of this poem is the only way to tell that the speaker isn’t already in Byzantium. Once we get to stanza three, in fact, it sure seems like the speaker has been in the city for a right long time. Hmm…are we on a journey or in a city? More specifically, are we going to Byzantium, or are we there already? Our heads are spinning just thinking about it. Well, the location of the speaker is actually one of the ambiguities of this poem. Don’t worry, it’s not the only one. Yeats has a whole stock full of strange things in store for us. The title, then, sets the stage for tension that only occurs once we move into the latter sections of the poem.
OK, so what does the title tell us about "Sailing to Byzantium"? We’re so glad you asked. Let’s focus for a second on the most important word in the title: "to." We know, we know: it’s a little word. It’s only two letters, in fact. It’s so little that it’s easy to miss. If we were being all fancy and technical, we’d say that "to" is a directional preposition. (Huh?) Because we’re not interested in all that technical stuff, though, we’ll just cut to the good stuff: using the word "to" means that the speaker is sailing to a new place. Moving on. Looking forward. Not obsessed with the past. You can fill in the rest...but you catch our drift. Travel is exciting. Byzantium is exciting. Why focus on a bad past when you can dream about an exciting future?