A couple of Rivers Seniors have built Rivers in 3D. Try as I might, I could not get my copy of Google SketchUp to render a proper .kmz file for Google Earth, but this is a big, detailed model:
They added all kinds of landscaping details (signs, benches, garbage cans, etc) and could not add colors and textures without slowing the animations to a crawl. But this was a tremendously fun thing to watch happen.