Mystery tiles - have you seen these?

[FollowThisLogic]

This freaked me out a little, because I know I've seen one of these things before. I'm pretty sure it was around Times Square.

An article was written about them by a guy who stumbled upon one in Kansas City, and decided to look further into it.

Apparently there are like 50 in NYC, 30 in Philly, and hundreds of others in cities all over the US... also two in South America.

So, have you seen one? Do you maybe walk over one every day without paying attention to it? <b>If you know the location of any, post them here!</b> Include the cross streets and which corner it's on, if you can.

(Apparently Toynbee.net is supposed to be the best resource for info on these, but it is currently suffering from the Slashdot effect...)