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Public-images-osm logo.svg site_type = crannog
The Crannog on Loch Achilty (geograph 3439802).jpg
A crannóg is a mostly or wholly artificial island used for habitation or as a workplace occurring in Ireland, Scotland and Wales.
Rendering in OSM Carto
Group: Historic
Used on these elements
may be used on nodesshould not be used on waysmay be used on areasmay be used on relations
Useful combination


Status: in use

A crannóg is a mostly or wholly artificial island/ islet created for human habitation. Most of them were constructed circular in shape, others were oval. They were constructed from historic:civilization=prehistoric up to the historic:civilization=medieval period and inhabited as late as historic:period=victorian times.

In some cases, they a modern re-creation for educational purposes in heritage parks as part of a tourism=attraction.


There are an estimated number of 2,000[1] crannógs in Ireland (110 are recorded in Co. Leitrim alone[2]), and there are 347 listed as monuments for Scotland[3]. Crannógs can vary in size from a diameter of c.10m to up to 40m[4] and were reached by their inhabitants by boat or causeway.

They can be found through local knowledge or historic maps (for example the British War office map for Ireland shows some of them with the label "Crannoge" or as circular islets with no label). Other resources to find them:

Some of the sites turn out not to be crannógs after all following archaeological excavations, so it is up to each mapper to make a judgement call to map it as an archaeological site or not depending on the available information.


Crannógs can be recognized on satellite imagery as an island with a circular (tree) outline or as circular features in the water. Sometimes, they are now on dry land due to changes in water level and could be mistaken as ringforts or similar land structures.

Historic sites

See further down below for modern reconstructions, i.e. experimental archaeology sites.

Draw the area or set a node with the following tags:

tag explanation
historic=archaeological_site Use only for genuinely "old" sites.
site_type=crannog Sub-classify site as crannóg.
place=islet* If still visible above water. Note that due to the elements working on the site over the centuries, the islet might not be of the same size as the crannóg and should be mapped separate.

* Note that at the moment place=islet overrides historic=archaeological_site, i.e. it will not be rendered as a historical site on the standard view on openstreetmap.org.

Additional Tags
tag explanation
historic:civilization=* Depending on when they were built and/or occupied (if known).
historic:period=* Depending on when they were built and/or occupied (if known).
heritage=* If certified as heritage. Use additional references according the the country applicable, where available, ref:IE:smr=* for the Republic of Ireland and ref:canmore=* for Scotland.
access=* These might be vulnerable sites, often on private land, so please indicate if they are accessible to the public or not.
wikimedia_commons=* Many of the Scottish sites have photographic representation on WikiCommons.

Experimental archaeology sites

tag explanation
site_type=crannog Classify site as crannóg.
place=islet Usually the same area as the crannóg itself.
access=* Depending whether they are part of a facility purely for research or accessible to the public.
tourism=attraction If it applies. They usually have a website=*.

Reconstructed crannógs usually have one or more huts with roof:material=thatch built on them.


Further information

Possible mapping mistakes

  • name=Crannog ‒ A crannog is a type of an archaeological site, please use at least the name of the lake or bog in combination with "Crannog".
If you know places with this tag, verify if it could be tagged with another tag.
Automated edits are strongly discouraged unless you really know what you are doing!