+--------------------------------------------------+
    |                                                  |
    |    +----------------+        +---------------+   |
    |    |                |        |               |   |
    |    |       A        |        |       B       |   |
    |    |                |        |               |   |
    |    +--------+-------+        +-------+-------+   |
    |             |                        |           |
    |             |                        |           |
    |    +--------+------------------------+-------+   |
    |    |                                         |   |
    |    |                   C                     |   |
    |    |                                         |   |
    |    +-----------------------+-----------------+   |
    |                            |                     |
    +----------------------------+---------------------+

         A   the room you are in
         B   the room you were in
         C   the room between them, which has no door

Every architectural plan is a lie about the third dimension. This one is a lie about the first two as well. Room C is drawn correctly and cannot be entered.