To dream that you are in some building that is build underground, means that you chose to separate yourself from the others. You will lose luck because of your choice. The underground could also indicate your desire for protection and shelter, because you do not feel safe while living the life. On the positive note, the underground indicates your ability to get away from all of the madness that is happening around you in everyday life.
Read more about dreaming of Underground in other dream meanings interpretations.