Okay, “Mappr” is a clumsy app. What I want to do is zoom in on a place and see what’s been taken there, but it appears that only tag-searching will take me to anything. I just tried searching their “collections” (pre-defined tags, I guess), and it’s still supposedly loading the photos. (I chose “Architecture”.)
But that Color Fields Colr Pickr is awesome. I can’t think just yet of a learning use for it — though it might be a good design/creation tool if it were used with public-domain photos.