In the mid-1980s, the art historian Lothar Haselberger found ancient, life-size architectural drawings incised on these marble walls, which enclose the inner court of the Temple of Apollo at Didyma (c. 300 B.C.). The drawings, which depict the various parts of the temple and methods of construction, were probably made to show later architects how to complete and repair the temple (which remained in use for 500 years). The drawings also help us understand Vitruvius. For example, Vitruvius writes that the temple’s architects, Daphnis of Ephesus and Paeonius of Miletus, developed a method of entasis (the construction of columns with a slight convexity to compensate for optical effects), and he refers the reader to one of De Architectura’s drawings—all of which have disappeared. Now, however, this aspect of Vitruvius’s text can be reconstructed from the drawing of entasis on the Didyma temple wall.