How to drag a chunk of the real world into VR?

In an ideal world we would just be able to specify an area of the world on a map and hit the play button to run/drive and shoot our way around in a 3d model of that region.

But using open source data and information (free), Blender and Unreal what are the best approaches to dragging a chunk of the world into Unreal?

Ideally I would like to be able to drag in a 10km x 10km area of the world into Unreal, is this even possible?

PS any additional tools or data must also be free to use.

So you want to have a real world landscape in your UE4? -> when yes, then take a look at this thread:

My immediate thought at the title of this thread:

If you have LIDAR scans of the area you want, or heightmaps if its a rural/mountainous area, then it should be doable.