Passageways are a common feature in many buildings, and can refer to a variety of structures. Ducts, aisles, and halls are all types of passageways. Ducts are typically used for ventilation or plumbing, and are usually made of metal or plastic. Aisles are narrow corridors that are often found in stores or churches, and are usually lined with shelves or pews. Halls are larger passageways, often with multiple rooms branching off from them.