Just think of them as glass buildings

 

So this one might look a little weird, but basically we're looking up and to the right from inside a building, we wouldn't be able to see anything usually but think about it if it was made of glass. The red squares are a section of the building at the same elevation, you can think of it like the same floor level, the diagram at the bottom right help illustrates that. The blue square on the left is the roof of the building, it's just colored blue to show its "inside" the building.