GeoNamesThe GeoNames Ontology is an OWL vocabulary that gives semantic structure to one of the world's largest open geographical databases. With over 11 million toponyms, each assigned a unique and stable URI, the GeoNames Semantic Web forms a critical piece of the Linked Data cloud, connecting place names to coordinates, administrative hierarchies, feature classifications, and related resources across the web.
Background
GeoNames began as a geographical database aggregating place name data from numerous sources worldwide. In October 2006, Marc Wick published the first version of the GeoNames Ontology (v1.0), giving every feature in the database a dereferenceable URI under sws.geonames.org. This was an early and influential implementation of Linked Data principles, predating much of the broader Linked Open Data movement. The ontology has been iteratively refined through multiple versions, with the current release being version 3.3 (July 2021).
Purpose and Scope
The ontology serves two complementary purposes. First, it provides a formal vocabulary for describing geographical features — their names, coordinates, feature classifications, administrative context, and relationships to neighboring places. Second, it acts as a Linked Data publication mechanism, making the entire GeoNames database available as RDF with proper HTTP content negotiation.
Key concepts in the ontology include:
- gn:Feature — the central class representing any geographical entity
- gn:GeonamesFeature — a subclass with a mandatory unique GeoNames identifier
- gn:featureClass and gn:featureCode — hierarchical classification of features (e.g., P for populated places, P.PPL for a populated place)
- gn:parentCountry, gn:parentADM1 through gn:parentADM4 — administrative hierarchy
- gn:nearbyFeatures, gn:neighbours, gn:children — spatial and hierarchical relationships between features
The ontology reuses established vocabularies including WGS84 Geo Positioning (wgs84_pos:lat, wgs84_pos:long), FOAF, Dublin Core Terms, Creative Commons, and SKOS.
Linked Data Architecture
GeoNames follows the httpRange-14 resolution by using HTTP 303 (See Other) redirects to distinguish between a real-world place and the document describing it. For example:
https://sws.geonames.org/3020251/— identifies the town of Embrun, France (the concept)https://sws.geonames.org/3020251/about.rdf— the RDF document describing Embrun
This pattern allows Semantic Web agents to correctly distinguish between the thing being described and the description itself, a foundational principle of Linked Data.
Each feature document links outward to related resources: children features, neighboring entities, nearby places, Wikipedia articles, and DBpedia resources, creating a richly interlinked geographic knowledge graph.
Serializations and Access
The ontology definition itself is published in RDF/XML (OWL). Feature data is accessible through several channels:
- Individual feature URIs — dereferenceable RDF for any of the 11+ million features
- Search webservice — with
type=rdfparameter to retrieve RDF results - Full RDF dump — approximately 182 million triples covering all features (as of February 2020)
- Database dump — tabular format for bulk processing
A separate mappings file provides equivalences between GeoNames feature codes and classes in Schema.org, LinkedGeoData.org, DBpedia, and the INSEE ontology.
Version History
The ontology has evolved substantially since its 2006 debut:
| Version | Date | Key Changes |
|---|---|---|
| 1.0 | October 2006 | Initial release |
| 1.2 | October 2006 | 303 redirects, linked data (contains, neighbours, nearby) |
| 2.0 | April 2007 | Added isOfficialName, locatedIn, GEMET concept relationships |
| 2.1 | June 2010 | Changed inCountry to countryCode, added license metadata |
| 2.2 | September 2010 | SKOS labels, parent admin division URIs |
| 3.0.1 | February 2012 | OWL 2.0 property chains, multilingual labels, schema.org mappings |
| 3.1 | November 2012 | GeonamesFeature subclass, explicit geonamesID property, historical feature codes |
| 3.2 | November 2019 | Contributed by Elisa Kendall |
| 3.3 | July 2021 | PPCLH and PPLH classification corrections |
Governance and Maintenance
The GeoNames Ontology is maintained by the GeoNames project, a privately operated geographical database. Marc Wick is the primary implementer. The ontology and data are licensed under Creative Commons Attribution 3.0 (CC BY 3.0), requiring attribution to GeoNames when reusing the data.
Updates are released as needed, with no fixed schedule. Community input is accepted through the GeoNames forum and direct contact.
Notable Implementations
GeoNames URIs are among the most widely used geographic identifiers on the Semantic Web:
- DBpedia and Wikidata — link to GeoNames URIs for geographic entities
- LinkedGeoData — cross-references GeoNames features with OpenStreetMap data
- Europeana — uses GeoNames for spatial context in cultural heritage metadata
- BBC — has used GeoNames in linked data publishing for news and programming
- Library of Congress — references GeoNames in authority data
Related Standards
- WGS84 Geo Positioning Vocabulary — reused by GeoNames for latitude/longitude coordinates
- Schema.org — mappings provided between GeoNames feature codes and Schema.org types
- SKOS — used for labels and historical notes on feature codes
- Dublin Core Terms — used for document metadata (created, modified dates)