Material-saving concrete ceiling made from 3D-printed interlocking blocks. A new modular design principle has the potential to revolutionize concrete construction: the concept of topological interlocking of building blocks. The innovative arrangement of these interlocking blocks effectively prevents kinematic loading of individual blocks by the entire assembly by immobilising each other. This study investigates the synergy between topological interlocking and 3D concrete printing and conducts a comprehensive analysis of the manufacturing processes and structural performance. The interlocking blocks, which interlock without binders, offer outstanding prospects for sustainable construction. The study presents a method for optimising block geometries for 3D printing to ensure interlocking integrity. Three specific block geometries are developed and tested for 3D concrete printing. Different methods are used to produce interlocking blocks in 3D concrete printing. A geometry is selected and tested on both a small and large scale in the form of a plate system. This is followed by experimental tests, including precise 3D photogrammetry measurements, to evaluate the structural behaviour of these plate systems. The results impressively demonstrate the feasibility and enormous potential of integrating topological interlocking and 3D concrete printing for sustainable construction applications.