A ballroom is a large room inside a building, the designated purpose of which is holding formal dances called balls. Traditionally, most balls were held in private residences; many mansions contain one or more ballrooms. In other large houses, a large room such as the main drawing room, long gallery, or hall may double as a ballroom, but a good ballroom should have the right type of flooring, such as hardwood flooring or stone flooring (usually marble).