When you know an identification number and the source it came from, you can use Pelias to get details on the location.
For now, the /place endpoint returns exactly the same data that any other would. However, in the future, we plan to allow more information, perhaps geometries to be returned here.
The /place endpoint accepts Pelias gid strings that get returned for every exactly matched record in query responses. These gid strings should not be built manually, but rather used directly as-is to lookup additional details on the location that gid refers to.
For example, this /place query looks up the Eiffel Tower in OpenStreetMap (OSM):
/v1/place?api_key=your-mapzen-api-key&ids=openstreetmap:venue:way:5013364
Note that you need an actual gid value to make a /place search. For example, if you search for an address and the result is interpolated, then there is no discrete gid to use for a /place search because interpolated results may be from multiple data sources.
To search for more than one /place in a request, join multiple values together and separate them with a comma. For example, this /place query looks up the Eiffel Tower in OpenStreetMap and the borough of Manhattan in Who's on First:
The results are returned in the order requested.
If you enter a valid gid that cannot be found or has "expired" due to a newer build, you may get empty results. The request will NOT return an error.
If the structure of your gid is invalid, an error will be returned as part of the GeoJSON structure.
Keep in mind that if you enter a gid that cannot be found in a list of multiple IDs, then the features array in the response contains a different number of elements than the number of requests. For example, your request may have three IDs requested but only two results returned. The reason for this is that the features section of the response is GeoJSON-compliant, and JSON does not allow a way to convey an exception condition (not even an empty JSON element, {}). For this reason, if your application is dependent upon the results mapping directly to the individual input requests in order, then you'll have to do your own bookkeeping to handle exception conditions.
Due to the ever-changing nature of most open-datasets used by Pelias, some gids can change merely by importing newer data.
Both Geonames and Who's on First have excellent, stable IDs and should not cause trouble. However, OpenAddresses and OpenStreetMap do not have stable IDs. Be careful.