https://vc.systems/loesungen/3d-stadtmodell/
https://www.geoportal-mv.de/portal/Geodatenviewer/
https://www.businesslocationcenter.de/berlin3d-downloadportal/#/export
https://github.com/smrcek/SU_CityGML_ExportPlugin
FZK Viewer (City GML) Umwandeln in STL https://www.iai.kit.edu/1302.php
https://osm2world.org/download/files/latest/OSM2World-latest-bin.zip