Chicago to Paris $493 Round-Trip on LOT

Valid through early March, on LOT (the Polish national airline).

http://www.airfarewatchdog.com/cheap-flights/Chicago-Illinois-ORD-to-Paris-Ile-de-France-CDG/

When you get to Paris, you can take any of the ultra-low-cost European airlines to other destinations including London, Madrid and Berlin.

Paris, France, Reachable at Low Cost on LOT Airlines