Getting BIM data into Unity (Part 1 - ArchiCAD)

This is part 1 of a series of posts about getting BIM data into Unity.
After our introductory post, we go through the basics of getting an ArchiCAD model into Unity.
Getting from ArchiCAD & Unity
The following model is the final result of my first series of Video Tutorials for ArchiCAD (recorded with ArchiCAD 16).
Taking ArchiCAD files into Unity is easiest when passing through Cinema 4D, using the Exchange Add-on, which allows ArchiCAD to export native C4D files and which has an option to integrate updates to the model, while retaining materials and animations in the Cinema 4D project.
Cinema 4D projects can be placed directly in a Unity project, in the Assets folder, which triggers a background FBX conversion. You can also opt to export the model manually which gives more control. Either way, you end up with the ArchiCAD geometry into Unity, following the structure and hierarchy that was visible in Cinema 4D.
Updates to the ArchiCAD model can be synced in Cinema 4D and consequently, be brought back into the Unity scene, while retaining animations, material assignment and all the rest of the project.
However, apart from the 3D meshes and the applied (basic) materials and positions for cameras and light sources, there is not much else surviving from ArchiCAD.
That said, the objects are grouped logically (if you opt for the by-class export option in ArchiCAD) and they retain their ArchiCAD ID as name. This was the hint for me to further explore how to get more information across. But more on that later.