The Room For $ 25 Million

Many houses are built to contain a box-room (box room or boxroom) that is easily identifiable, being smaller than the others. The small size of these rooms limits their use, and they tend to be used as a small single bedroom, small child's bedroom, or as a storage room. Other box rooms may house a live-in domestic worker.
Traditionally, and often seen in country houses and larger suburban houses up until the 1930s in Britain, the box room was literally for the storage of boxes, trunks, portmanteaux, and the like, rather than for bedroom use.