A 3D multi-user environment developed during the Underground City 3D/XXI project inspired by the Sierpinski Pyramid and the Labin ex-coal mine structure. Space developed using parametric and procedural architecture principles with the unity3D game engine. It's a space of presentation where to discover Underground City visual identities created first as 2D compositions and then extruded as 3D volumes. It's a space where the past, presented as video samples from the Labin ex-coal mine archives, is interlaced with visions of the being immured in the contemporary media society. It's a tango between lights and shadows which cross the small apertures of nowadays social bunkers. You can there use different collaborative tools, like a chat, a painting tool, a drawing trajectories tool, shared text boards and more.