Once I had a chest full of treasures.
The only thing left of it is the cage where I kept them.
I have no money anymore. Not that I need any.
I am used as a base to build things.
I didn't leave my room for years.
I feel in my bones that it won't change.
For some I am an armour.
For some I am a coat hanger for all they are.
Who/What am I?
EDIT: Added second stanza to narrow the question