If the brain functions like a computer processer, then deciphering its circuit should give us insight as to how it works. In fact, modern tools used in the semiconductor industry scan, inspect, or clone the wiring and billions of transistors used in a computer chip. With several hundred million synapses connecting all the nerve cells, a simple fly brain has the complexity close to that of modern processors and should be amenable to reverse engineering. The imaging challenges are however very different with the brain being a highly varying interconnected 3D structure while semiconductor circuits are self-similar with largely 2D layouts. This has driven the development of new 3Dl electron microscopies that can resolve the requisite nanometer detail while spanning 3D distances approaching a millimeter. We will present such data for the case of the fruit fly brain, discuss the barrier of automated wiring reconstruction, and explore how such connectivity information might clarify brain function.