What's Your Favorite Location in a DnD Setting/Module?

Hi! I'm currently prepping a campaign where the gist is the PCs are traveling through the multiverse and throughout different timelines. I thought something fun would be to visit different settings and modules to kind of showcase some of the unique locations, quests, and NPCs that the DnD multiverse currently has to offer.

So, what are some of your favorite places you've visited in DnD and why? What made that one quest so special? What memorable encounters has your party faced?