Where the city ends
I've always been fascinated with where urban environments "end"… where does city become… something else.
Here in Berlin—and I saw the same in Vienna this past weekend—the city very quickly and abruptly, on some segments of its periphery, dissolves into some form of rurality. Fields, mountain-side wine plantations. (Where I come from, Montreal, the city slowly fades into suburbia in most directions, where it is not bordered by river or industrial land.)
The above screencap is of course from Google Maps, which recently turned on isometric (pseudo 3D) building outlines for Berlin.
As in the physical world, the virtual city here stops at some physical borderline: train tracks , or a small river or stream.
Notice in the satellite view also how the trees are greener (more plentiful) on the other side: