The "Me" cave is a technique I picked up, and I really couldn't tell you where, but it's quite useful in keeping track of oneself - learning about myself, fixing issues in myself, and seeing what is coming on the horizon for myself. It's the first room I come to in a Shadow Journey, and it really determines where I go from there.
The "Me" cave is divided into four quarters, one each to represent the four common elements: Air (I think of it as Wind), Fire, Earth, and Water. In the center is a circle cut out to represent Spirit. There are walkways between each of these elements, and the walkways are lined with items relevant to the element. Earth then is often lined with rocks, Air sometimes has fog lining its borders, water has a moat (if it's not a pool that day), and fire has candles or a wall of flame. Spirit's border... is generally not seen, but shivers when you cross it.
You may have noticed from this description that the borders are not set each time I visit. In fact, the contents of each "room" take on a life of their own, and this in fact is the point of the "Me" cave.
The inside of each room changes based on what is needed at the time. The condition of each room is the way the "Me" cave communicates to me my internal status at the time. If I'm having issues grounding for example, the "Earth" section will need attention in some way (if I'm out of whack on that element), or there will be something in the Earth section that will indicate that there is a greater need for this element at the moment, such as a depiction of an earthquake.
Typically the central point of the "back wall" of each of the four basic elements contains a statue or an altar that relates to that element. The statues are almost always of me, outfitted to suit the element. I tend to think of each of the statues as different "Girls" (Wind Girl, Fire Girl, Earth Girl, Water Girl, Spirit Girl) within myself, and their elements need to be kept in balance. The girls tell me my relationship with each element at the time, and by their positions and garb I can often tell just what I need at a given time in that element. The altar generally contains fetishes of some sort for each element. The contents of the altar can tell me what I need to know, if the altar is the dominant element of the quarter. There can also be statues (or the presence of) the spirit helper I have for each element. If all three items are present, the statues of the helper and the Element Girl are generally on opposite sides of the altar; other times the two statues are combined into one figure. All of these end up in positions, situations, or with contents that have meaning if interpreted properly to give me a warning, or answer a question, or give a status report, or... really anything they can communicate that I am able to understand.
The spirit realm was added to the room after it had already been in use for several years, and I honestly couldn't tell you how it got there. Since my spirit helper is a tree, however, it is that tree which grows out of the ground of the cave, and shoots up through the top of the ceiling. There are branches inside the cave, which also help to give insight into the situation in its realm. This element is almost always outfitted with a few "park benches" to allow me to sit and meditate on the situation, or a convenient root for the same purpose. This element is the most bare of the elemental areas; while the altar and statue have been sighted there, usually the tree is alone and I read it. Note also that in the Spirit realm, my helper is always present. This is not the case for the other elements; in fact the only times they usually meet me in their elemental sections of the room is when they are taking me somewhere, have a message for me, or just want me to lighten up and go play with them.
All my shadow journeys pass through this room on their way to wherever they go. Sometimes coming to this room is an end in itself; sometimes it is my place to prepare myself for the journey ahead.