Poetry Puzzlers: Can you figure them out?

Here are three riddles, written in the form of a poem.  Can you figure them out?  Have fun and good luck!

1. 

He who builds me doesn't want me,

he who buys me doesn't use me,
he that uses me doesn't know he's got me.

What am I?

2.

I tower over the man-made plain;
My peaks scrape the heavens.
I have many brothers; in fact,
We may be as many as a hundred and seven.

We're as ancient as the oldest trees,
But not older than the hills.
We've been studied for centuries now,
But with mystery we're still filled.

3.

I have streets but no pavement,
I have cities but no buildings,
I have forests but no trees,
I have rivers yet no water.

What am I?

No peeking at other comments until you write your answers!  :)