Wow. That's really impressive. Here is more background:

https://magazin.wienmuseum.at/die-387-haeuser-des-peter-frit...

And the virtual exhibition of the museum:

https://sammlung.wienmuseum.at/alben/edb7nhc3tyww8dncp-sonde...

Some of the models contain a rail segment (Märklin etc.). Was he a model train enthousiast and the houses were part of a layout, or did he use the rails just as accessories? Strange that the articles don't say anything about the artist's motivation.