To see through buildings
1. look up straight up far as you can with an gun other objects may work. walk backwards into any walls then hold "ALT" and look around . then you can see through the building.
other way to see through walls is to hold "Q" or "E" when u are close to the wall or structure then use "ALT" to look about through the wall or structure.
To see through hills you do something with laying down. I don't know how to do this every time but there is a way of doing this perfect quickly every time.