I was fascinated to discover this mosaic on Martin Luther King Day, of which I had never heard:

St. Francis of the Guns
Beniamino Bufano, 1898-1970
1969, bronze, gunmetal, mosaic tile

Commissioned by the mayor of San Francisco after the assasinations of John F. Kennedy and Martin Luther King Jr., made of voluntarily donated handgun metal from 2000 handguns, inlaid with mosaics of King, Kennedy, and Lincoln.

A Pilgrimage to Walls Speak:  The Narrative Art of Hildreth Meiere