The city scape model came on a MDF board. it is fastned with tie rips. But the board also is part of the art if you ask me. I wanted to put it all on the wall. The hiegth of the tie rips 2 mm so the offset from the board to the wall is 5 mm. I added holes and a resess for double sided tape. 

It is not possible to screw all four in the wall, but the forces on the top fasners are a lot lower so i used tape for those two.