Toynbee Tiles?
 

Anyone else ever heard of these or know anything about them?

There was an article in the KC Star a few days ago, which points to this site. Apparently, you Philly folks have several of these embedded in streets around your fair city.

http://www.toynbee.net/

Check out the "gallery" area for pics.

Cool whacko stuff!

Pretty bizarre. I would point out that a paint stencil can be made that won't show any lines between the outer and inner part of the letter.;)