Tesseract bubbles

A tesseract is the 4d extrapolation of a cube. If drawn in 2D it looks like a cube within a cube. The 3D version would appear as above. If you could interact with a tesseract in 4D it would appear as a room in which each wall was another room of the same size. if you walked in one direct , say forward, then the third room that you enter would be the same room that you started in.However if you walked backwards,left, right, straight up or straight down, the third room that you enter would be the room where you started as well.

Thank you, I should have been more clear. I don't understand the I shaped building bit.

Oh. I'm sorry. By I shaped building I meant That when you leave the center by going left,right,forward or backward into an "adjacent" room,if you then go up or down you still end up in the same room that you would have found up or down from the origin room.

Ah, thanks.