One hundred years ago, Alois Alzheimer used a simple light microscope to examine brain samples from a 51-year-old female who had died after a long battle with dementia. Through the observations, conducted during his time at the Königliche Psychiatrische Klinik in Munich, Germany, he identified structures characteristic of the patient’s condition, which fellow physician Emil Kräpelin named after him in 1911.In 1907, Alzheimer used Max Bielschowsky’s silver impregnation technique to stain a fragment of cerebral cortex tissue (left) from a patient presenting with what he called presenile dementia. In a 5× magnification of the image, cellular details begin to emerge (right).Using its Mirax digital slide system, Carl Zeiss of Jena, Germany, has taken a collection of glass microscope slides created by Alzheimer and put them in electronic form. Imaged and archived, the groundbreaking work can be distributed among researchers and viewed repeatedly in high resolution without risking damage to the original material.A closer look at brain tissue from Alzheimer’s landmark patient displays telltale signs of the disease. At 20×, amyloid plaques and neurofibrillary tangles become clearly identifiable (right). Plaques appear as distinct dark splotches; tangles look thin and elongated. Both are thought to result from abnormalities in protein processing that accompany the condition.Collected from an individual who showed symptoms similar to those of Alzheimer’s landmark patient, a sample from 1911 reveals the various histological manifestations of the illness (left). In a 20× image of the sample, large plaques are visible, but no tangles (right). Cared for at the Königliche Psychiatrische Klinik directed by Emil Kräpelin, the patient was probably the first person clinically diagnosed with Alzheimer’s disease.