The apartments now reach almost half the way up the hill and the model is starting to resemble the real building.
The grey sides of the model are attached at an angle to each floor in a very simple and space efficient way, that allows the studs to be aligned exactly at the wanted position. This is shown on the two pictures below.
This picture shows a subset of the apartments shortly after the building was completed. The plants have yet to grow big.
In my Lego version the green plants are more visible which corresponds to the current state of the building as seen on the image below.
Finally, a view from the top.