I have many ideas for a campaign that I am going to be running, but I am having a difficult time coming up with a starting point for building the world. I want to build something that is out of the ordinary. I don't want a world that feels like your standard European setting on a traditional medieval continent. I want something that has a slightly more unique feel to it. For example,

The world consists of continents which float through the air above the ocean

Or,

The world takes place underneath the planet's crust, with the core acting like a pseudo sun that floats in the center of the world with gravity pushing outward

Or perhaps,

The planet itself is actually a vast living creature which floats through space.

Something along those lines. Does anyone have any other thoughts such as these which might spark inspiration?