The Kasthuri lab is pioneering new techniques for large volume reconstructions of the fine structure of the nervous system – ‘connectomics’. I will describe these developments including: large volume automated electron microscopy for mapping neuronal connections, synchrotron source X-ray microscopy for mapping the cellular composition of entire brains and combining both for multi-scale, multi-modal maps of brains.  I will also describe out efforts to combine electron and x-ray microscopy with current techniques for interrogating the proteome and the genome.  These tools will be applied in the service of answering the question: how do brains learn as they grow up?  And how do brains differ across individuals and across species?