New illumination was installed in 1985 to light up the tower from within, and it was the obvious main focus of France's celebrations for the change of the millennium in 1999.
The New Illumination was not in place to celebrate the new millennium.  
mnli hypothesis: The New Illumination was not in place to celebrate the new millennium.   premise: New illumination was installed in 1985 to light up the tower from within, and it was the obvious main focus of France's celebrations for the change of the millennium in 1999.