OSNI Open Data: 50,000 Townland Boundaries in Ireland

50,000 vector polygons showing townland boundaries across Ireland, derived from the Ordnance Survey Northern Ireland (OSNI) Largescale database. The dataset has been topologically cleansed to create a seamless polygon layer. It is published for OpenData by the Government Digital Service under an Open Government Licence.

Use Cases

• Genealogical research based on the ancient townland land measurement system mentioned in the description.
• Historical land use analysis based on the small, varying-sized land area polygons.
• Creating base maps for Ireland based on the seamless, topologically cleansed boundary dataset.
• Integrating administrative boundaries into web or desktop mapping applications based on the available geospatial formats.

Strengths

• Contains approximately 50,000 boundaries, providing mid-scale coverage.
• Data has been topologically cleansed to create a seamless dataset.
• Available in multiple standard geospatial formats (KML, GeoJSON, ESRI Shapefile).

Limitations

• Row count and dataset size are unknown, which may limit suitability assessment.
• Column-level documentation is absent; field semantics must be inferred after download.
• Last update date is unknown; freshness unverified.

Provenance

Source

Ordnance Survey Northern Ireland (OSNI) Largescale database.

Collection Method

Derived and topologically cleansed from the source database.

Time Range

null

Freshness

Last updated date is unknown.

Geography

Ireland