In 1993, to coincide with the opening of Toulouse's first metro line, the exhibition Les Couleurs du Métro – Fifteen Artists, Fifteen Stations brought together at the Centre Culturel Aérospatiale the fifteen artists selected to create works for the fifteen stations of the new line.

From its inception, the Toulouse metro gave contemporary art a distinctive place within its architectural program: each station was to feature an original work conceived in relation to its surroundings and permanently integrated into the public space. GRATALOUP was selected to create the work for Bellefontaine station.

The project brought together several major figures of contemporary art, including Olivier Debré, Hervé Di Rosa, Richard Di Rosa, François Morellet, Takis and François Bouillon. In Toulouse, GRATALOUP thus found himself alongside several artists he knew and with whom, despite the diversity of their individual practices, he shared an interest in extending art beyond the traditional spaces of museums and galleries.

For Bellefontaine, GRATALOUP conceived a monumental work bringing three distinct elements into dialogue: a 6 × 10-metre mosaic, an inclined sky plane measuring 1.70 × 10 metres, and two inverted pyramids forming a fountain. Color, light, geometry and water were brought together in a single composition conceived on an architectural scale and designed to become part of the passengers' everyday experience.

The exhibition presented the approaches of the fifteen artists involved in this ambitious public art commission. It reflected a conception of contemporary art that, in the early 1990s, increasingly engaged with the urban environment: the artwork moved beyond the confines of museums and galleries to enter the city and become part of everyday life.

The project was also documented in the 1993 catalogue Quinze artistes dans le métro : Toulouse, published by MT Développement, with texts by Pierre Rey, poems by Serge Pey, and photographic portraits by Marie Clérin. GRATALOUP was given a dedicated presentation in the publication, documenting his participation in this major program integrating contemporary art into Toulouse's public spaces.