On 22 January 1967, Simon & Garfunkel performed at Philharmonic Hall at Lincoln Center in New York City. For the poster, Milton Glaser put both musicians literally on a pedestal, and gave their iconic silhouettes the same three-dimensional treatment as he used for the characters in his (Glaser) Baby Fat — illustration follows typeface, for an inimitable graphic gesamtkunstwerk.
Original copies of the poster go on eBay for a couple hundred dollars. The music can be had for less: A recording of the concert was released in 2002 as Live from New York City, 1967. Baby Fat is not available in digital form, but there is Buxom, an adaptation of the Black style, made by Fotostar/Facsimile Fonts in 1975, and Keepon Truckin NF, a revival made by Nick Curtis in 2007. As far as I know, there is no digitization of the Outline style that is used here.