It began ten years ago, maybe more. It started in Philadelphia and rapidly spread to New York City, Boston, Baltimore, Washington. It has been sighted as far afield as Santiago, Chile and Rio de Janeiro. Maybe you've seen it. Maybe you haven't. But now you know what to look for --- a block of text, flat on the roadway, a little larger than a computer screen.
Bill O'Neill keeps a web page tracking the phenomenon at ToyNBee. Another page describes how they're done. If you get really fascinated you can Google for more, though Bill's page already links to most of the major articles available online.
To claim this cache, upload two photos: one of just the tile itself, and another of the tile in the context of the intersection. If circumstances permit, take a third picture, with both your GPSR and the tile. I want you to do this for two reasons: roads are regularly resurfaced and the tiles won't last forever; and building a set of coordinates will help us see if the tiles form some kind of urban crop circle with (who knows?) a hidden meaning visible only on a map. Many roads have been resurfaced since the tiles were originally laid, so get cracking before they all vanish!
This is a locationless cache so the rules require GPS coordinates. Entries lacking them will be deleted. Getting a good signal may be challenging because of the "urban canyon" effect; having a map-enabled GPSR will help.
Please check to make sure the tile you find hasn't already been found by somebody else. Remember, it only counts if you're the first person to find a particular tile; if you find a tile somebody else has already logged, your entry will be deleted (Sorry, but that's the rules!)
11/01/05: Adopted from Freeside.