A ceiling provided with a plurality of rigid panels. Presser means tending to press each panel longitudinally against at least one adjacent panel. At least one panel is a “sliding panel” carried by a guide device so as to slide in a sliding plane. One panel is a “retractable panel” movable from an open position towards a closed position, the sliding panels being free to move in longitudinal translation along the guide device when the retractable panel is in the open position and being locked while being arranged longitudinally one after another when the retractable panel is in the closed position. The ceiling comprises movement means for moving the retractable panel in reversible manner from the closed position to the open position.