Aaannnddd Done. --Unofficial Contest: impossible geometry

Well, I guess it doesn't work on people...
-----------------------------------------
hurhurhurhurhurhurhurhurhurhurhurhur
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Rules:
1. Can contains anything.
2. Must be a structure that can work (not appearance only) and impossible to achieve in real world due to geometrical restrictions. For example: endless hallway, looping stairs and so on.
3. Must allow derivatives so I can check it.
4. Must be a derivative of this level.

Credits to Sasha from Russia