Delta Airlines has a $605 round trip ticket price for July travel from Chicago to Berlin TXL. Departure dates at this fare are available May through early August.
Delta Airlines Chicago ORD – New York JFK – Berlin TXL – New York JFK – Chicago ORD
These tickets can be booked as Air France or KLM codeshares too.
KLM ticket for Delta-operated flights booked as Air France codeshares.
Chicago ORD – New York JFK – Berlin TXL – New York JFK – Chicago ORD