The dome is often the first stage of the trip. It can begin as a 2d image, unfolding to open a 3d space where entities of various sorts seems to be greeting and welcoming the tripper.
Hyperspace Lexicon description :
The Chrysanthemum : A gigantic, often spinning, kaleidoscopic fractal flower with a domelike appearance that turns into a doorway, either welcoming or blocking access to breakthrough Hyperspace.
Terence McKenna description :
“When you break into this space, you have several impressions simultaneously that are a kind of gestalt: First of all (and why, I don’t know) you have the impression that you are underground – far underground – you can’t say why, but there’s just this feeling of immense weight above you but you’re in a large space, a vaulted dome. People even call it “The DMT dome” I have said, had people say to me, “Have you been under the dome?” and I knew exactly what they meant.
“I visited the chrysanthemum once. I was at the peak of shrooms, ripped the dmt, and experienced an infinitely unfolding fractal flower, blue and pink, complete and instant ego death. I also briefly seemed to tap into another human or entity’s consciousness and memories, which was shocking and radical, however it was but a vague recollection once the trip was over.”
“I see it often at the beginning of the trip. Sometimes the walls are full of Hindu iconography, sometimes I see cat faces everywhere. At the top of the dome there is a kind of door. It appears circular to me and I often can see things coming from the door before I get through. There is often some kind of guide or guardian there, with the appearance of an old bearded man or a feline creature. After that I am in another space.”