One embodiment of the present invention provides for a subterranean structure, having a continuous ribbon slab having a plurality of flights fabricated from concrete. The ribbon slab defines periodic openings therein which generally align between adjacent flights. Another embodiment provides for a method of fabricating a subterranean structure. The method includes excavating soil to form a downward sloping ramp, and forming a concrete slab on the downward sloping ramp. The method further includes continuing to excavate soil to extend the downward sloping ramp to a location under the concrete slab, and continuing to form the concrete slab on the downward sloping ramp so that a subterranean structure is formed having an essentially continuous concrete slab with a first portion which is above and spaced-apart from a second portion.