In Constant Nieuwenhuys' New Babylon, a visionary project for a utopian city, the Yellow Sector refers to one of the colored zones or areas that symbolize different functions or characteristics within the city.

New Babylon was designed as a city for homo ludens (the playing man), where work would be automated, and people would be free to explore, create, and live without constraints. The different colors in his models represented zones of varying social or experiential functions.

While there is no fixed definition for the colors, the Yellow Sector in New Babylon is typically interpreted as a zone symbolizing light, creativity, and joy—a space where inhabitants are free to experiment and express their creativity in an open and fluid environment. In the context of his work, colors often carried symbolic weight, suggesting a mood or atmosphere rather than a specific functional zone like in traditional urban planning.

Constant’s vision was that these sectors would continuously evolve, with the inhabitants shaping the space according to their changing desires and activities.