As part of the modernizing and extension of the museum from 1999 to 2005, the lighting concept was thought to reignite the presence and breadth of daylight that Charles Girault initially designed for all exhibit halls, which deteriorated over time due to the progressive concealing of skylights and windows.

This historical monument was built in the Art Nouveau style for the 1900 World Fair and is centered on an indoor garden. It is witness to this era, which celebrated natural light.

The solar orientation of the many rooms, the great window openings, the wide variations in light levels based on the time of day, the weather or the seasons, required complex artificial lighting choices, adapted to each geographical situation. The subtle mix of artificial and natural light, and their integration in the museum space are such today that visitors cannot, without a view to the outside, decipher where each comes from.

The peripheral, Southern halls, very bright, are equipped with a monumental chandelier in polished glass, which hangs above the center of the space and continuously trails through each room.