Disco balls - such as the one illuminating legendary disco dancer Alfred E. Neuman on the cover of MAD above - are a totemic symbol of the disco era. Nevertheless, contrary to what you might expect, your great-grandmother may have danced the Charleston under one, at least if she happened to have lived in a city in Europe or the US in the early 20th century. Although it wouldn't have been known as a disco ball at the time, the mirror ball (or glitter ball, ball mirror, or specular sphere) graced dance floors as far back as the late 19th century.

You can spot them in the still below from the nightclub sequence of the wonderful 1927 silent film Berlin: Symphony of a Great City, or, in the original German, Berlin: Die Sinfonie der Großstadt, directed by Walter Ruttmann, and scripted by none less than Karl Freund and Carl Mayer.