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Public-images-osm logo.svg defensive_works
Vestingwerken schema.svg
Military constructions or buildings designed for the defence of territories in warfare Show/edit corresponding data item.
Group: military
Used on these elements
may be used on nodesmay be used on waysmay be used on areas (and multipolygon relations)should not be used on relations (except multipolygon relations)
Documented values: 3
Useful combination
See also
Status: approvedPage for proposal

This key is used to tag individual defensive structures mainly at historic/pre-modern  fortifications. It is intended for all structures that were built for the defence of territories in warfare. This includes fortified settlements as well as forts that are/were uninhabited during peacetime.

Values for defensive_works=* contain terms used in fortification engineering.[1][2][3][4][5]

How to map

Individual defensive works should be mapped as node Nodes at their centre, as way Ways along a centre line or as area Areas along the outlines. The best fitting method depends on the size and shape of the structure. They should be tagged with defensive_works=* and may receive additional tags.

Mappers are encouraged to combine this tag with other tags where they are relevant. If a structure is actively used by the military, it is recommended to add a military=* tag to it.


Key Value Description Sample photo
defensive_works barbican A  barbican Barbakan Krakow z ulicy Basztowej 2.jpg
defensive_works bastion A  bastion. The tag defensive_works=demi-bastion also has minor usage. Komárno - Castle.jpg
defensive_works battery A  fixed artillery battery.

Individual guns or cannons can be tagged with historic=cannon.

Battery Ledyard Angel Island.JPG
defensive_works batardeau A [W]batardeau[6] PL Batardeau 2015.JPG
defensive_works caponier A  caponier Gorazda fortress ditch and caponier.jpg
defensive_works cavalier A  cavalier Malta - Birgu - Ix-Xatt tal-Birgu - Fort Saint Angelo (MSTHC) 02 ies.jpg
defensive_works counterguard A  counterguard Rochapea1.JPG
defensive_works counterscarp A  counterscarp Antwerpen Schansstraat fort VIII, reduit met droge gracht en contrescarp (links) - 391094 - onroerenderfgoed.jpg
defensive_works couvreface A  couvreface Maastricht, Linie van Du Moulin, droge gracht tussen couvreface Du Moulin & bastion Stadhouder 1.JPG
defensive_works crownwork A  crownwork Luchtfoto bourtange.jpg
defensive_works curtain_wall A  curtain wall. See also  defensive wall. Courtine dame blanche.JPG
defensive_works faussebraye A  faussebraye is a lower wall in front of the main defensive wall of a fortification. Heusden onderwal.jpg
defensive_works glacis A  glacis is an artificial slope that is part of a fortification. Glacis field jersey.JPG
defensive_works hornwork A  hornwork Nicpmi-01514-1-birgu fortifications hornwork of the post of castile.jpg
defensive_works inundation_sluice A  sluice made for  military inundation Fort Everdingen Inundatiesluis.JPG
defensive_works lunette A  lunette or demi-lune is an  outwork in the shape of a half-moon. LünetteII 1.jpg
defensive_works moat A  moat that historically provided a fortification with a preliminary line of defence.

For moats filled with water, add the tags natural=water and water=moat.

Dourdan castle dry moat.jpg
defensive_works motte A  motte Launceston Castle - - 22242.jpg
defensive_works ravelin A  ravelin Vestingwerken P1060601.JPG
defensive_works redan A  redan Redan Naxxar 3.jpeg
defensive_works redoubt A  redoubt Ximenes Redoubt in Salina, Naxxar, Malta.jpg
defensive_works reduit A  reduit Reduit.JPG
defensive_works roundel A  roundel Rondella della Bacola.jpg
defensive_works tenaille A  tenaille Tenaille, Fort Manoel.jpg
defensive_works water_gate A  water gate Newport Castle.jpg
defensive_works User-defined Use technical terms in fortification engineering. Table of Fortification, Cyclopaedia, Volume 1.jpg

Tags to use in combination

  • name=* - if a defensive structure is named. Do not use the name of the fortification to tag individual structures.
  • heritage=* - if the structure has a heritage status. If only the entire fortification has a heritage status, do not use heritage tags for individual structures.
  • building=bunker - if the structure is a  bunker
  • start_date=* - year of completion
  • abandoned=yes - if the structure has been abandoned and shows signs of decay
  • ruins=yes - if the structure is in ruins

Similar and related tags