The agency is responsible for conserving the character and history of the sites, while facilitating their use for culture, business and experiences.

Three forts, Austrått, Møvik and Trondenes, were built by the German Wehrmacht during World War II as part of Festung Norwegen.

Oscarsborg has received an opera stage, while Kongsvinger has been partially converted to conference center.

Costs of maintenance is split between rental income from events and tenants, and government grants.

Responsibility for the sites was transferred to the National Fortifications Heritage, when it was established as a division within the Norwegian Defence Estates Agency.