Frankfurt is a hugely trafficked airport in the center of Germany (and all of Europe) , so its no surprise that there are often quite a few cheap flights to here from Washington DC.

Frankfurt is also a great jump off point to other European cities, as it has a very active train station with many trains going to all major and minor European cities.

Flight Details:

Flights are non-stop on United. I also found some cheap flights with American Airlines and Lufthansa, but $520 is for the United flight.

Flight time is 7-8 hours for non-stop flights.