Answer:
If a man carries my burden they will get crushed to death. Though not rich I leave silver in my track.
I may seem real but it always turns out I was never there in the first place... you only see me during a certain resting stage.
When you buy me I am costly, but the only use I have is hanging only. What am I?
What building has the most stories?
I move without wings, between silken strings. I leave as you find my substance behind. What am I?
Before Google, we actually had to physically look things up in this building full of knowledge.