Since the 1980s hundreds of cryptic plaques have appeared across the streets of America. Embedded in the asphalt, the material forming the tiles remains mysterious. Likely made of layers of linoleum, tar paper, and asphalt crack-filling compound, each plaque begins life as a dark black smudge, slowly curing before wear uncovers the message hidden beneath. Their name’s origin, given for the title “Toynbee Idea” that … Continue reading The Toynbee Idea