The Macroverse

Roland refers to the Macroverse as a "void of possibility which lay beyond all physical worlds":

"Mort had not died of fright; the gunslinger felt with a deep instinct which was the same as knowing that if Mort died, their kas would be expelled forever, into that void of possibility which lay beyond all physical worlds. Not dead—fainted. Fainted at the overload of terror and strangeness, as Roland himself had done upon entering the man’s mind and discovering its secrets and the crossing of destinies too great to be coincidence." -The Gunslinger

There are no directions in the Macroverse to speak of:
Richie, no! Go back! It’s the edge of everything up here! The deadlights!
souns like what you turn on when you drivinn you hearse at midnie, senhorr . . . and where is you, honeychile? smile, so I can see where you is!

And suddenly Bill was there, skidding along on

(the left? right? there was no direction here)

one side or the other. And beyond him, coming up fast, Richie could see/sense something that finally dried up his laughter. It was a barrier, something of a strange, non-geometrical shape that his mind could not grasp. -IT

The Macroverse's existence dates back to before the Prim receded:

"Maybe once, just after the Prim withdrew and Gan’s voice still echoed in the rooms of the macroverse, the Beams were smooth and polished, but those days are gone. Now the Way of the Bear and the Turtle is lumpy and eroded, full of coves and cols and bays and cracks, plenty of places to get your fingers in and take hold, and sometimes you drag at it and sometimes you can feel yourself worming your way into it like a drop of acid that can think. All these sensations are intensely pleasurable. Sexy." -Song of Susannah

This is important, because it also means the Macroverse predates Gan's creation of time as a concept:

“Gan created time,” Roland said. “This is what the old legends say. Gan rose from the void—some tales say from the sea, but both surely mean the Prim—and made the world. Then he tipped it with his finger and set it rolling and that was time.” -The Dark Tower