Answer:
I am two-faced but bear only one. I have no legs but travel widely. Men spill much blood over me. Kings leave their imprint on me. I have greatest power when given away, yet lust for me keeps me locked away.
In we go, out we go. All around and in a row. Always, always steady flow. When we'll stop, you'll never known. In we go, out we go.
What goes through the door without pinching itself? What sits on the stove without burning itself? What sits on the table and is not ashamed?
Through its wounds, water does run. It once held many but now has none. What is it?
I grow where no flower grows, where no light touches the walls, up or down, that I don't care, was here before people were.
I met a man on the London bridge, he tipped his hat and drew his name, in this riddle I told you his name. What is it?