What's the most expensive bike?

Excuse me, I was wondering if you could help me with a question. I'm really interested in bicycles, and I'm curious to know, what's the most expensive bike on the market right now? I've heard about some really high-end, luxury bikes that are practically works of art, but I'm not sure which one takes the cake in terms of price. Do you happen to know which bike holds that title? I'd love to learn more about it.