Because we were saddened by the general state of the CityGML websites, we have now taken over the official domain: www.citygml.org.
We currently have, among others, the following:
Anyone who also loves CityGML is more than welcome to contribute to the site by submitting new content and/or fixing errors. We are particularly looking for new software, and a more exhaustive list of ongoing developments.
The source code is publicly available and hosted on GitHub, and if you want to contribute please visit this page.
Cheers, The gurus of CityGML