The process of polychromatic architectural illumination (dubbed "chromolith") was created and developed over 5 years by Patrice Warrener in the early 1990s, the first creation of its type was presented on the facade of the Opera Garnier in Paris for the Grand Gala des Arts et Métiers. It followed, approximately, a hundred achievements of this type everywhere in France, in particular at the Festival of the Lights of Lyon where he intervened on the city's major buildings for more than twenty years. They also appeared throughout Europe and all over the world for various light festivals, or other events (Singapore, Dubai, Melbourne, Orlando, Kobe, etc.). The last important illuminations took place in London on Westminster Abbey and in Quito on the basilica and the La Campagna church 2 years ago, and for the "fiesta de la luz" in December 2019. The Montfalcon portal of Lausanne cathedral was resplendent with colours every evening. The illumination of the splendid gothic facade of Our Lady of the Sablon will constitute a first for Brussels. This highly detailed facade is the best place for a chromolith architectural illumination.