Along Moreland Avenue, at the tail end of Little Five Points, there's a big vacant lot, with the remnants of a building foundation in the middle. Nothing particularly different than dozens of places around Atlanta, but unusually, the tile floors shown above are still there.
The tile was divided into three sections, and I'm presuming it was a bathroom (there's holes that would seem to match up to fixtures, now overgrown with weeds). The floors are a bit richer aquamarine than you can see up there.
No clue what the building once was -- there hasn't been anything there as long as I can remember (though I probably didn't walk along Moreland much before last year). A gas station would be my best bet, since there's something filled in where pumps may have been -- but it's not as obvious as some other defunct stations around town. If anyone stumbles upon this and has a better idea, it's just south of Sabroso's/Front Page News, and it looks like the lot is used for parking at night.
Anyway, not a lost Roman mosaic or anything, but I always thought it was kinda cool.