The world is a bright civilized place. People have colonized the Earth, the Sea, and finally the Air. Using mysterious anti-grav technology floating cities coast along above the clouds. Sky Cities tend to fall into two categories: port cities and pleasure cities. Port cities are vibrant, exciting places, rife with crime. Some port cities are notorious for their criminal activity, others have a strong police force in place. Pleasure cities serve little purpose at all, and often times answer to a ground-based government with only private security in place on the actual sky city.

Sky cities are considered autonomous, unless built and launched by a ground based government. Even so, a sky city will often decide to declare freedom from the government that created it, and there's not much that can be done about it. Wars are never fought with sky cities because of their delicacy; if they were to be destroyed they would fall, and destroy the city beneath it. Therefore most sky-based disputes are settled in a complicated game of cat-and-mouse politics.

That sounds like it will provide some interesting events for a story.

If most sky cities built by ground based governments break away, then why do the ground based governments bother to make them, since I would imagine it's pretty expensive?

They don't anymore.

So... are the pleasure cities privately owned vacation spots for ground politicians? The port cities sound like fun. How do people get back and forth between?

Ooh, I love this idea. What kinds of cat-and-mouse politics are we talkin' about?

So I take it there was an era in which a lot of these floating cities were built, and then the phase kind of faded because it wasn't profitable when they all revolt anyways?