In vitro study of high-level neurobiological systems requires three-dimensional (3D) neuronal cultures [1]. Meas-uring responses along all three spatial dimensions is critical to record electric activity inside 3D neuronal models, such as organoids and other 3D brain tissue constructs. However, this lies beyond the capacity of 2D microelec-trode arrays (MEAs) [2]. We present planar arrays of 3D micro-pyramids, whereby each micro-pyramid supports multiple, electrically distinct and vertically stacked microelectrodes. The 3D microarrays were produced by wafer-scale micromachining and assembled onto printed circuit boards (PCBs) conforming to MEA readout standards.@en