 In a famous 1959 speech considered to mark the birth of nanoscience and nanotechnology as fields of study, Richard Feynman charged scientists with the problem of measuring, manipulating, and controlling things on the atomic scale. Since then, scientists have used electron microscopy to successfully resolve distances millions of times smaller than a pinhead. But Feynman's vision of identifying the three-dimensional coordinates of individual atoms in a material remains elusive. In this study, scientists have taken a significant step toward meeting Feynman's challenge by using a technique called electron tomography to map the locations of 3,769 atoms in a needle made of tungsten. Electron tomography works by using an electron beam to produce images of a microscopic object along different orientations. Those images are processed by a computer to visualize the three-dimensional structure of the object. In this study, scientists rotated a tungsten needle over a total angular range of 180 degrees, capturing snapshots of the needle's tip at different intervals. Before the snapshots were combined into a single 3D image, they were corrected for stray movements of the sample and other distortions during imaging. The images were then reconstructed using two different methods for reducing noise. Regions in each reconstruction where the intensity produced by the electron beam exceeded a certain threshold were labeled as candidate atom sites. When both reconstructions identified the same candidate site, a real atom was likely to be found there. Statistical analysis showed that the 3D positions of atoms could be determined with a precision of 19 picometers, much smaller than a hydrogen atom's radius of 53 picometers. With such high precision, the researchers were able to accomplish a rather difficult feat in the world of material science. They were able to see how the actual atomic structure of their tungsten sample differed from its ideal crystal structure. Not only could the researchers detect the absence of an atom in a location where it would normally occur, they could also quantify how much the atoms were shifted from their predicted positions in a perfect lattice, mapping the 3D displacement from the ideal one atom at a time. This capability transcends the limitations of traditional electron microscopy because it allows individual atoms in an object to be accounted for in three dimensions. The resulting images therefore provide a more complete picture of how atoms are arranged in real samples than the traditional electron microscopy images currently found in textbooks. This marks the first time that the positions of thousands of individual atoms have been detected in three dimensions without assuming the crystallinity of a sample material. Paving the way for novel applications in physics, chemistry, nanoscience, material science and biology and coming one big step closer to meeting Feynman's challenge.