Built in 1993, this memorial of Martin Luther King, Jr. is hidden behind a small waterfall. Apart from King's photo, there are also several glass panels with excerpts from his famous speeches. Interestingly, each quote is not only provided in English but also translated into the languages of San Francisco’s sister cities.
Wikipedia https://en.wikipedia.org/wiki/Yerba_Buena_Gardens#Public_art
Official website http://yerbabuenagardens.com/public-art/
Address Yerba Buena Gardens, 750 Howard St, San Francisco, CA 94103, United States
Coordinates 37°47'4.311" N -122°24'8.114" E