A planetarium of the 21st century should be a reflection of the worldview that is common today as well as our differentiated way of life. Contents that are conveyed are the new mysteries of our decade: the space-time continuum, the journey through wormholes and ideas of infinity. Thanks to the latest technology, especially mixed reality, the actually built geometry can be used as a support surface for the superimposition of analog and virtual reality. In the virtual, infinity can actually be experienced. In the physical, we only ever experience a snapshot. By means of fractal structures, the transition between finite real space and actually infinite virtual algorithm becomes stepless. The built geometry and virtual algorithm are identical, the real structure is just one iteration in the creation process. In the new Haus der Raumzeit, the visitor experiences on the one hand space, i.e. space, and at the same time virtual immersion. Formally, the building manifests itself in a grid, which shows that time is always and everywhere in all directions, it only becomes physical on the construction site. At those points where all three directions meet, based on Interstellar’s Tesseract, moments in time. On the one hand, these are glass boxes of memory, that is, filled with earlier ideas of the cosmos and the universe, or with the transfer of knowledge.