IdRef ID

http://www.wikidata.org/prop/direct/P269

Used as a Predicate in:

Schema Name	Schema Link
city	https://www.wikidata.org/wiki/EntitySchema:E100
museum	https://www.wikidata.org/wiki/EntitySchema:E125
UNESCO world heritage site	https://www.wikidata.org/wiki/EntitySchema:E142

Used as an Object in:

Schema Name	Schema Link
museum	https://www.wikidata.org/wiki/EntitySchema:E125
UNESCO world heritage site	https://www.wikidata.org/wiki/EntitySchema:E142