In an appendix to their article ‘Lute-Players in Greek Art’ (JHS lxxxv [1965], 62–71) R. A. Higgins and R. P. Winnington-Ingram included useful material on the shape of the kithara, with a list of representations that attempt to show the depth and shape of the back of the kithara sound-box. The list includes a mid-sixth-century metope from Delphi, back views from late fifth-century to late fourth-century coins, Hellenistic terra-cottas, and a back view on a late second- or early first-century relief, Athens National Museum 1966. These more-or-less three-dimensional objects show us a characteristic of the kithara that may affect the possibilities of playing technique, one that cannot be guessed by looking at the many front-view paintings: the back of the kithara soundbox bulges out at the top, tapering toward the base; and in examples from the fifth century and later, it rises to a vertical ridge running down the centre of the back.
To this group of objects should be added one more important item from the fifth century: the back view of a kithara which is part of the Parthenon frieze of the Panathenaic procession (447–432 B.C.).