Woo!

Just to be clear, are we talking about soley the exterior or does this include the little fore-rooms with elevators?

Whether you go right to an elevator or enter and can look around before descending, is entirely up to you. Generally speaking, the "above ground" portion of the sub-gate is what we're looking for. Though if there were a partially unearthed or semi-collapsed design, that would certainly create a gray area.