To understand the human brain, an international consortium of scientists has created the most complete atlas of this organ to date. The map reveals the anatomy, the architecture of the tissues, how or where each cell is, their function, gene expression and regulation. On Oct. 12, 2023, Science and Science Advances published a group of 21 studies that unveiled the map of the human brain, as well as the brains of nonhuman primates and mice, cell by cell, for an adult model and for the different stages of development.