A foldaway balcony comprises a platform structure tiltably mounted on a wall and a rail structure mounted to the platform structure. The platform structure comprises a box-like support structure and a planar floor structure which are tiltable relative to the wall separately from each other. The rail structure comprises a plurality of rail elements, which are hinged at the edge of the support structure of the platform structure, and are tiltable between a stored position, in which they lay within the support structure, and a deployed position, in which they stand relative to the support structure. When the platform structure moves from the closed position to the open position, first the support structure is tilted, then the rail elements move from the stored position to the deployed position, and finally the floor structure is tilted.