Answer:
Golden treasure I contain guarded by hundreds and thousands. Stored in a labyrinth where no man walks Yet men come often to seize my gold. By smoke I am overcome and robbed then left to build my treasure anew.
I start in little but I end in full you'll find me in half and complete.
What is so delicate that saying its name breaks it?
I go through a door but never go in, and never come out. What am I?
I run around the city but I never move.
What is lighter than what it is made of?