I am a student and fairly new to AutoCAD, I have been stuck on this issue the last two days and would be really grateful for some help. I am trying to make an isometric view of a map I can put into photoshop for part of my site analysis, the map and building heights are imported from CADMapper. All the building have a thick outline around them and I can't work out why or how to remove it. Alternatively I can put it into '2D wireframe' but then you can see all the geometry which I also don't want want! I am working on a MacBook Pro, I have attached both screenshots and my file. Please can somebody explain how I can resolve this, 

Thanks in advance,

Grace