A semi mobile fortress placed in the mouths of rivers, bays, and other bodies of water up to several miles off shore
A hoary old tower that serves as the lair of a necromancer, but not is all as it seems.
I know a guy who says he found a tower in the woods and saw a man fall out the window - straight up!
Sid and Jir were childhood friends growing up in the same town on the ocean. Both creative geniuses, both with the need to be better than the other. Many will tell you that this friendship created their genius while others realized, in hindsight, that it spelled the lands doom.
This really comes from an ancient Chinese novel. Imagine during the PCs' travels, they come to a place where the gender roles are completely reversed. What adventures will the PCs encounter in such a place?