Answer:
Thousands lay up gold within this house, But no man made it. Spears past counting guard this house, But no man wards it.
It can pierce the best armor and make swords crumble with a rub, yet for all its power It can't harm a wooden club.
I am black when I am clean and white when I am dirty?
Iron roof, glass walls, burns and burns and never falls.
What is that which, though black itself, enlightens the world without burning?
What language does a billboard speak?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?