Answer:
There is an ancient invention still used in some parts of the world today that allows people to see through walls. What is it?
Spies and detectives do this to phones and musical shoes make this sound.
Before Mt. Everest was discovered as the highest mountain in the world, which mountain was the highest?
I can be as thin as a picture frame but my insides have many things you can see.
What has roots that nobody sees, and is taller than trees. Up, up it goes, and yet it never grows.
Two little holes in the side of a hill. Just as you come to the cherry-red mill.