The B1B4 tower is a residence for researchers located at the edge of Paris in the new Massena Bruneseau neighborhood. This area is characterised by a duality between aerial towers and the presence of heavy underground infrastructures of transport. The project responds to this duality by distinguishing two opposite parts. The tower’s heavy concrete podium deals with the public sphere of the street, the ground and the underground. Its hosts “the house of researchers”, a program of collective activities meant to encourage physical encounter. The upper part addresses the sky and the nearby towers. It is characterised by a wooden structure covered by a glass façade. It hosts the researchers’ housings. This duality responds to the typical life of researchers alternating between moments of intense loneliness dedicated to research work, and moments of encounter where they meet, relax and exchange their ideas.