This drawing looses it's "top" when imported

This .dwg file won’t import correctly. What’s up?
base1.dwg (21.1 KB)

Any ideas would be appreciated.


How should it look like?
My import looks like this:

If you mean that there is no face on the other side, like below, I don’t know why that happened, but it is trivial to fix. Just open the group for edit and redraw any of the back edges.

If the model should lie flat on the ground, it is incorrectly modeled in AutoCad. It is placed on the red/blue plane (XZ in AutoCad). In both AutoCad and SketchUp the “ground” plane is supposed to be the XY/Red-Green plane. Was this modeled in one of the old-style 3D applications the view the world as a “stage”?