We fabricate artificially designed micro-environments to culture and probe living cells. Arrays of defined cavities provide standardized geometric boundaries for individual cells or groups of cells. We study single cell gene expression, cell migration and apoptotic events with precise spatio-temporal control. To this end we develop biofabrication techniques, including photo-lithography, hot-embossing, electroplating, soft lithography, 3D printing and microcontact printing, to create two-dimensional (2D) and three-dimensional (3D) pattern, cavities and channels made of biocompatible materials like PDMS, COC, hydrogels and proteins. The 3D microenvironments allow for long-term observation of growth and function of individual living cells, interacting groups of cells and organoids.