An illumination system is described including a plurality of illumination devices, each device including (i) light-emitting elements (LEEs) arranged along a corresponding first axis; (ii) an optical extractor extending along a corresponding longitudinal axis parallel to the first axis; and (iii) a light guide positioned to receive at a first end of the light guide light emitted by the LEEs and guide it to a second end of the light guide. The optical extractor is optically coupled to the light guide at the second end and is shaped to redirect the light guided by the light guide into a range of angles on either side of the light guide. The illumination devices are connected to each other to form a polygon such that the longitudinal axes of the connected illumination devices lie in a common plane.