Resource enclosure is a tag in Age of Empires III introduced in update 13.58326, referred to as AbstractResourceEnclosure in the game files. They are buildings which control map natural sources of resources either by preventing them from being gathered by enemy villagers, or dealing considerable damage with a large Area of Effect. Although the tag was created in update 13.58326, units had attack multipliers against the very same individual resource enclosure buildings before that update as well, creating a misconception that these units had gained attack multiplier against resource enclosures and lost the attack multiplier against those buildings in that update.
Like normal buildings, resource enclosure buildings are vulnerable to artillery and siege units. Villagers also have a ×3.0 multiplier against them for their siege attack, while Bow Riders have a ×1.5 multiplier instead.
The following buildings are labeled as resource enclosure:
| Tags in Age of Empires III | |
|---|---|
 Infantry | |
 Heavy infantry | Hand infantry ·  Pikeman · Musket infantry |
 Light infantry | Foot archer · Rifle infantry · Hand skirmisher |
| Other | Counter skirmisher · Grenade trooper |
 Cavalry /  Shock infantry | |
 Heavy cavalry |  Hand cavalry · Ranged heavy cavalry · Lance cavalry |
 Light ranged cavalry | Gunpowder cavalry |
| Shock infantry |  Hand shock infantry ·  Ranged shock infantry |
| Other | Camel · Elephant |
| Siege units | |
 Siege unit ·  Artillery ·  Siege Elephant · Gatling Camel* · Fixed Gun* · Arrow Knight* | |
 Ship | |
Fishing boat · Warship ·  Recruiting ship | |
 Building | |
Resource enclosure ·  Wall · Frontier fortification · Barracks | |
| Other | |
 Hero ·  Mercenary · Monk ·  Outlaw ·  Pet ·  Villager | |
| Mother nature | |
 Huntable ·  Treasure guardian | |
| Support tags | |
| Gunpowder unit · Archer · Healing unit · Native warrior · Elephant · Camel · Archaic infantry · Ranged infantry · Ranged cavalry · Consulate unit | |
| All tags with icons are related to the bonus and penalties counter system, except *hidden tags that aren't in the UI | |