So! Dylann is a great big cavern. (think D'Ni, if you're a myst fan. I was heavily inspired by Myst while writing this.) There's a river that runs east to west through it. The city of Kaverna is built on this river, just west of the waterfall. The river has its source in one of the crystal forests, where the Sadinese Ambassador has his palace.
There are twelve gates leading to the surface. These gates are watched by Gatekeepers, who serve as both guards and emissaries, greeting the travelers, keeping the peace, and enforcing both Dylann's laws and the laws of whatever land lies on the other side of the gate.
Not all of these gates are named yet, since the rest don't come into play until the sequel and you all know me. I don't plan a book until after I write it.
(The Mishkal Gate is also from the sequel, but I started writing it during nano so I know that part and... whatever.) Anyway, here's the current gate layout: North
The Cordez Gate
The Avar Gate
The Lannah Gate
Unnamed Gate
South
The Mishkal Gate
Gate 2
Gate 3
Unnamed Gate
East
The Sadin Gate
Haven’s Gate
West
Selvor’s Gate
The Gateway to the Unknown
Four Gates north of the river (and Kaverna) four to the south, two to the East (above the river's source) and two the the west. (where the river exits.) I'll eventually start a thread for each of the gates and come back to link to them. While the openings were originally natural, they've been enlarged and expanded to be actual doorways with actual gates. After the Betrayal, all the gates were automatically closed and locked. Once closed the gates can only be opened from the inside.