We are very happy to see that North Rhine-Westphalia has released as open their 3D city model.
It covers a gigantic region, and both LoD1 and LoD2 models of the buildings are present.
Buildings are stored both with
gml:MultiSurface, and the semantics is present, which is 👍.
Our only concern is that the files are CityGML v1.0, while v2.0 has been out since 2012; but we will forgive them this oversight.
Download here the CityGML files, but watch out, it’s enormous: more than 286GB of zipped GML!