Skyhold is a fortress in the Frostback Mountains and serves as the headquarters for the restored Inquisition.
Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such as ciment fondu.
An exemption is concrete because concrete is often used from a mixture of non-metallic minerals that have been crushed or ground into small, fine pieces. These are called industrial minerals because they are used in the creation of many different products. For example, glass is made from sand, silica and limestone.