Mount Nevermind:

                LEVEL 0:         LEVEL 1:     LEVEL 2:      LEVEL 3:

                    O
                   / \
                  O---C-O
                  |   | |
              ? O-O-P-B-L
              |    \  |                                        Pl
              O     O-O                                        |
              |       |         Pl            Pl               O
              O     O |         |             |                 \
              |     | |         O-O-O-O-Lp    O-O-O-Lp           O-Lp
              O   T-O-O                                          |
              |     | |                                          O
          out O-O-O-O G                                          |
           :  |/      |                                        O O
           E  O       O-O                                    C.|/
           :          |                                      ?-B-Sh
           :          O                                        |
           :         /                                         ?
           E..O--O--O


 E  - Elevator
 G  - Gnomeflinger
 T  - Toolstore      
 C  - Cafeteria (food+drinks)
 P  - Post Office                  
 B  - Board    
 L  - Pole (landing spot when coming from higher levels)
 Lp - Landingplace from Gnomeflinger
 Pl - Pole to lvl 0
 C  - Common Board
 Sh - Shop