How is the Dowager's warren described in the novel, Wildwood (Wildwood Chronicles)?

The Dowager's warren is made up of a large network of tunnels and rooms that serve a variety of purposes. In addition to storerooms for food and weapons, there are rooms for training and socializing. There is a large throne room for meetings with the Governess. Her ornately carved throne sits on a dais which is covered in soft moss. Attendants are always nearby to attend to her needs.

The interior of the warren is all dirt which is supported by a mass of tree roots and vines underneath a large tree on the surface. Torches illuminate the passageways. One of the caverns has a vertical exterior opening through which the crows come and go.