Before there was any such thing as fast food, Harvey House restaurants once dotted the landscape from Chicago going West to California. I believe that there was large Harvey House restaurant at Chicago Union Station but it was located in the adjacent train shed building that was demolished years ago. This restaurant was a part of the railroad era of the early 20th century. Today only the name only remains on several independent restaurants and in museum buildings. All this was before my time but it must have been great being able to dine on fresh cooked food while waiting.in the station. If you are into nostalgia there is a place that I imagine is somewhat similar to Harvey House two blocks from Union Station on Jackson Blvd.( Route 66) , It's called Lou Mitchells.and its been there since 1923.
http://www.loumitchellsrestaurant.com/