Abstract: A displaceable knocked-down building unit defining a playing enclosure for use as a court for off-the-wall games. The unit has rigid external skeleton structures on the inside of which are secured wall panels thereby defining the playing enclosure. The means securing the wall panels of at least one wall which is to serve as the ball-bouncing wall are secured wholly on the outside of the panels whereby the said panels form an inner face for ball-bouncing purposes which is flat, continuous and devoid of projecting parts.