lucy24 - 9:46 pm on Nov 22, 2012 (gmt 0)
The earth doesn't have lines of latitude and longitude conveniently drawn on it. Bummer.
On my wall I have a photo map of Venice at a scale of-- they say-- 1:3623. I will take their word for it; it means that each of its 3-inch squares is about 300 yards. The fine print says the pictures were taken over a 3-hour period on one date in 1982.* Look closely and you can see the places where shadows-- and in some cases the buildings themselves-- don't line up perfectly. And I think we can stipulate that curvature isn't significant at that scale :)
* There's also some technicalia about what kind of camera was used. They didn't just go out there in a helicopter with a Nikon.