What am I?

Round and round, never off the ground. What am I?

related riddles

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

When set loose, I fly away. Never so cursed, as when I go astray. What am I?

You saw me where I could not be. Yet, often you see me. What am I?