Relief of the muse playing a citara. Hellenistic, second century BC. The craftsmanship shows Neo-Attic features. From Manyas. Marble.

From the Wikipedia: The cithara or kithara (Greek: κιθάρα, kithāra, Latin: cithara) was an ancient Greek musical instrument in the lyre family. In modern Greek the word kithara has come to mean "guitar" (a word whose origins are found in kithara).

The kithara was a professional version of the two-stringed lyre. As opposed to the simpler lyre, which was a folk-instrument, the cithara was primarily used by professional musicians, called citharedes. The barbiton was a bass version of the kithara popular in the eastern Aegean and ancient Asia Minor.