A new fly-through of the fly brain allows anyone to whizz past neurons and visit any of the 40 million synapses where neurons touch neuron. It's a super-resolution view of the complex network connections in the insect's brain that underlie behaviors ranging from feeding to mating. What's unprecedented, however, is that this 3D map over the whole fly brain, which shows details as small as 60 nanometers across, was captured in less than three days. While the level of detail is not quite as good as that obtained with an electron microscope, efforts to fully map the neurons and synapses of the fly brain with EM have taken 10 years and the efforts of dozens of people. The new map was obtained a thousand times faster by combining two state-of-the-art techniques, expansion microscopy and lattice light-sheet microscopy. (#34478)