I’ve seen them in New York.  I’ve seen them for decades now.

These strange tiles embedded in the pavement and sidewalks.  With strange writing.

They are all over the world, including Russia and Chile, but mostly in the United States.

Here’s what Wikipedia says about them:

Toynbee tiles (also called Toynbee plaques) are messages of mysterious origin found embedded in asphalt in several major cities in the United States, and in three South American capitals as well. As of 2006, there are approximately 130 tiles, which are generally about the size of an American license plate but are sometimes considerably larger. They all contain some variation on the following inscription:

TOyNBEE IDEA
IN KUbricK’s 2001
RESURRECT DEAD
ON PLANET JUPiTER.

Some of the more elaborate tiles also feature cryptic political statements or exhort readers to create and install similar tiles of their own. The material used for making the tiles was long a mystery to enthusiasts, but evidence has emerged that they may be primarily made of layers of linoleum and asphalt crack-filling compound.

Articles about the tiles began appearing in the mid-1990s, though there are some stories that earlier references may have started in the mid-1980s.

Websites have devoted themselves to the origin and meaning of the tiles.  The tiles obviously refer to the movie "2001", and Toynbee is probably a reference to mid 20th century historian Arnold Toynbee.

But aside from guesswork, nobody really knows what’s going on.

However, a new documentary about the tiles may provide the answer.

According to Sploid, Toynbee tiles may be the doings of a guy named James Morasco, a social worker in Philadelphia who died in 2003.  He reportedly believed:

…we could colonize Jupiter "by bringing all the people on Earth who had ever died back to life and then changing Jupiter’s atmosphere to allow them to live." Morasco discovered these ideas while reading the works of Arnold Toynbee. He also believed Toynbee’s ideas of resurrecting dead people’s molecules were depicted in Stanley Kubrick’s monumental film of regeneration and growth, 2001: A Space Odyssey.

Well, that seems to explain it. 

Unfortunately, Morasco’s widow doesn’t know what the hell anybody is talking about.