Interiors use the same gated game mechanics as instances but are not typically considered instances. Interiors are buildings, caves and other inside locations in Middle-earth that are populated by friendly NPCs. Characters can usually enter interiors by opening a door and passing into a separate instance from the outside world. Most interiors are located within a settlement such as the Scholar's Enclave in Duillond or The Prancing Pony in Bree.
For a complete list of interiors throughout Middle-earth see Category:Interiors.