A three-dimensional structure for armoring a motor vehicle is made of a steel plate and has a substantial hemispherical shape. The structure is reinforced by bending edges having an X-shaped configuration extending over the entire surface of the structure. Arranged between the legs of the X-shaped portion are sections which have surface areas between the legs of the X-shaped portion. The surface area of the X-shaped portion has a generally concave curvature, whereas the surface areas of the sections 11 have convex configurations in relation to the concave surface area of the X-shaped portion.