How is the city of New York on the website of the cesium official website made?

I want to know if it was made from the SHP file, if not, I want to be told the detailed process or the road map.

The input data for the New York data set was CityGML. We ran it through our CityGML to 3D Tiles tiler which will be part of the upcoming Cesium ion SDK. Our tiling tools are closed source at the moment so unfortunately I can’t provide a detailed process. However our recent blog post contains a high level overview of the steps involved: https://cesium.com/blog/2018/02/06/citygml-testbed-13/.