I think I was standing on the steps of the Grande Arche de la Défense when I took this.
In 1988, the building, now surrounded by office towers and a vast public plaza built over a network of subway and rail stations, was gutted and renovated. It was re-opened as the Centre des Nouvelles Industries et Technologies (still le CNIT). Office buildings and a hotel were built under the roof, totally transforming the space that was deemed insufficient for modern trade shows. It was after this renovation that I saw the interior -- the only time I've been inside the building -- and when I took this photo of the roof being power-washed.
The building was renovated again in 2006, still with office buildings inside, but re-built to better highlight the original vaulted roof and to improve connections to the outdoor plaza above and the pedestrian corridors and rail facilities below. I feel like I should go back and see it again the next time I'm in Paris.