Once upon a time there was an awesome maps company called Mapzen https://mapzen.com/. All of their software was open source and all their data sets were licensed under a free license.
Sadly they are shutting down https://mapzen.com/blog/shutdown/.
One of their projects was Who's on First https://www.whosonfirst.org/ which is a gazetteer https://en.wikipedia.org/wiki/Gazetteer of places. The data is a huge collection https://github.com/whosonfirst-data/whosonfirst-data of geojson files hosted on github.
The place files include a concordance of ids in other systems... including Wikidata. :)
Mapzen used the data in Wikidata in their Places API https://mapzen.com/documentation/places/ (source code https://github.com/whosonfirst/whosonfirst-www) to translate place names.
I'm not sure if we would have any interest in using/importing this data in Wikidata, but I thought I'd make more people aware of an awesome free license data set that needs some help now that Mapzen is going away.
Thanks for everything you do! David Barratt