Yggdrasil III

"Leaves rustled, alive with sunlight. He stood beside an ash tree whose trunk was mightier than a mountain and whose crown reached higher than heaven. Those boughs spread as wide as all the worlds, and he knew that three roots ran down to three of them, the worlds of the gods, the giants, and the dead.
"Wind tossed his hair."
-Poul Anderson, War Of The Gods (New York, 1999), XXXV, p. 295.

It is the final chapter. Hadding/Njord has died and is back where he belongs but that is quite a complicated cosmography to visualize. (See also here.) Where are the other six worlds?

I think that I have exhausted Yggdrasil as it is presented in Poul Anderson's works. There is also an introductory summary in Neil Gaiman's Norse Mythology. The myths live as long as there are authors like Anderson and Gaiman.