Okay, this place has bugged me for a long time. So I did some research and, combining what I could glean with what I have already exposed you to, these are my ideas of the layout of the Courts. As players, let me know if any of this is confusing, or if you have different ideas of how it is and why, or any suggestions about it.
The abyss is a huge circular pit. Within the center of this pit is a floating black citadel of immense proportions, the official Courts of Chaos. The citadel is the size of a small city, and much may be contained within. About much of the border of the Abyss is the City of Chaos, wherein most Houses have their official location, commerce and dealings mainly take place, and where characters in the group who have been to the Courts have been.
On one side of the Abyss shadow spreads out. On the other, the domain is highly dangerous and demon ridden, and few have claimed to explore it at all.
To get to the Citadel one can use what are called affectionately (?) filmies, ghostly tendrils which float and move above the abyss. Those with Logrus claim to be able to control filmies.
The black road extended over the Abyss to the Citadel.