Answer:
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. Sooner or later everybody needs my help yet many people are afraid to let me help them.
The Titanic is still here. What am I?
I have cities but no houses I have mountains but no trees I have water but no fish. What am I?
They took me from my mother's side where I was bravely bred and when to age I did become they did cut off my head. They gave to me some diet drink that often made me mad but it made peace between two kings and made two lovers glad.
My first though water cures no thirst my next alone has soul and when he lives upon my first he then is called my whole.
No matter how little or how much you use me, you change me every month.