The ISS with its 73m x 108m Integrated truss structure, apparently, is the largest (by dimensions) artificial object in space.
I know about the Krab experiment which produced two self assembly rings of 20m diameter, attached to a Progress spacecraft. That gives 40m x 20m.
Both Space Shuttle orbiter and Mir station were a bit shorter than 40m.
Neither of thin object such as IKAROS solar sail (20m) or Znamya reflector (20m) come even close.
The Inflatable Antenna Experiment's struts were shorter (28m) too.
So the question is: have there been any (other than ISS) artificial objects longer than 40 meters in orbit?