Mysterious 'Toynbee' Tile Uncovered In Manhattan

If you walk in New York York City, you’ve probably stepped on, over or around license plate-sized markers embedded in the streets of busy intersections and never noticed them. But a Tribeca Film Festival staffer, familiar with the so-called Toynbee tiles, stumbled on one recently that was covered with tar. She then called on her colleagues to take a look at the mysterious tile. They apparently appeared first in Philadelphia in the 1980s then showed up in major cities around the world.