We think that, as a symbol of death and sorrow, there's nothing more important in this poem than the tomb. On top of that, it's just a really vivid image, sort of rearing out of the wilderness like that, without much warning. It's the thing that finally breaks through the speaker's amnesia, and makes him realize where he is and what happened there.
- Line 76: Wham. The speaker and Psyche are "stopped" by the tomb. In a way, so are we. All of the imagery we've seen so far is natural, part of the world of the woods. Now, here's something man-made, cut out of stone. It's a totally different thing from the lake and the skies and the trees.
- Line 79: The tomb has some writing on the door (also a first for this poem). That writing turns out to be the name of his lost love, Ulalume. It's the first time we've heard this name. In a way, then, the tomb is introducing us to this important character. It's also a symbol of the cold, hard fact of death.