Titles held by the Biblioteca Hertziana - Max Planck Institute for Art History (BHMPI) for the city of Rome, inside the Aurelian wall.
The basis for this mix are:
the geographical keywords extracted from the Kubikat catalogue (B3Kat Open Data);
the references between GND and Wikidata Ids (Wikidata);
the polygons with Wikidata IDs provided by OSM (Turbo Overpass).
This is very much a prove-of-concept: please be merciful and notify us (email) of any inconsistencies. The data itself is available for download as GeoJSON (EPSG:4326).