What am I?

I am a protector. I sit on a bridge. One person can see right through me, while others wonder what I hide. What am I?

I was known to Greek philosophers a thousand years ago, I have numbers all in a line, and I can tell you if rain will turn to snow. What am I?

I can be naked, I can be covered; but just keep me peeled, and the wonders you'll discover. What am I?

I have no doors but I have keys I have no rooms but I do have a space you can enter but you can never leave what am I

Riddles and Answers