Note:

All files herein are created for

    Sketchup 8 and above
    
CityGML surface types are classified in different layers and are visible and usable in native Sketchup, 
further CityGML specific features ( like Location Info, Surface Types, Grouping and Attributes ) are stored in the models but are only visible, editable and usable with

    CityEditor plugin from 3DIS ( see https://www.3dis.de/cityeditor/ )

Note the licensing conditions in the LICENSE file ( also referenced to in the model info of each Sketchup file )