Berlin Tempelhof Airport
Howard heads in for another bland day at the office in episode 1x01 “The Crossing”. The Other Side's Howard heads comes to cross over on a 72-hour visa in episode 1x02 “Birds of a Feather”. Ian heads into work in episode 1x03 “The Lost Art of Diplomacy”.
Appears in 2 additional episodes.
Both Sides Now
This world's Howard meets up with Peter to cross over disguised as his other.
Shaking the Tree
Three agents from the Other Side get into a car with blacked-out windows and later Aldrich searches the archives for evidence of the mole.
Source: Chicago Lawyer/Author Larry Judd