I was lucky, the data also included lat/lng and the address for most (if not all) the entries.

If I would have been confronted with such a situation though, I would have probably used some Geocoding API like Google Maps's geocoding [0] or OSM's Nominatim [1].

[0]: https://developers.google.com/maps/documentation/geocoding/o...

[1]: https://wiki.openstreetmap.org/wiki/Nominatim