Most invasive brain research is done on model species like mice and rats, but for many neuroscientists the ultimate goal is to understand the human brain. Small biopsy samples of human brain can be acquired from medical surgeries and prepared for large-scale electron microscopy. This opens the opportunity to investigate the ultrastructure of the human brain directly.The Lichtman Lab at Harvard collaborates with several hospitals which make tissue samples available to us which would otherwise be discarded. In our largest electron-microscopic dataset to date, we acquired over a Petabyte of image data from a piece of adult human cortex, which we are currently analyzing in collaboration with the Google Connectomics team. In this talk I will highlight some of our recent findings on the ultrastructural properties of human cortex.