Abstract: An underground hangar for storing helicopters includes an underground room (1), made by a structure of reinforced concrete (2) inside which a plurality of columns (11) are situated near the walls and anchored to the floor of reinforced concrete. The columns (11) support a platform (10) which moves between the ground level and the underground level. The helicopter can land on the platform (10) and be automatically brought to the underground level, after which the underground room is automatically closed by the doors (8) and the pilot can go out through an adjacent underground room (1a) provided with its access trap door (4).