Thoracic cross-sections of the human body
More than a century before the Visible Human Project brought together almost a dozen sources of millimeter-thin cross-section cuts of the human body to create interactive 3D models, people were already freezing and carving bodies into slices to show the inner form of the human body.
The cross-section and topographical anatomy textbooks were intended for medical students, whose access to real humans/cadavers would not have allowed this particular visualization of how the human body comes together.
An Atlas of Topographical Anatomy: after plane sections of frozen bodies. Wilhelm Braune, translated by Edward Bellamy, 1977.
Source: archive.org