The gates aren't that high, so no matter where you climbed it, you would eventually see the wreckage of Sector 7. Given they come out out onto a solid surface that has no buildings around it, I'm inclined to say you come out on sector 6, and find an opening in the ring that circles around it.
But I've said on a number of occasions that Midgar is a poorly defined city. Most of it is literally copy-pasted, such as the fact that each sector has what appears to be the exact same turreted bulding and smoke stack combination towards the edge.
I just started playing Silent Hill, and the size of each of the sectors feels roughly the size of the entire town there, if anyone wants a sense of scale. It's big, but maaaaybe not as big as what many people have imagined the city to be. So Wallmarket combined with the broken highway leading to it could probably take up the same size as Sector 6 itself. It's difficult to tell because Square so clearly didn't have continuity in mind.
Combine that with how indistinct all the areas look, and its kinda clear Square just wanted a concept, rather than a fully functional city. I'm very curious how much of the teaser trailer is intended to actually be physical locations, as there's no way some of those locations fit into the structure of Midgar as we know it.
I will be VERY impressed if Square doesn't try to cheat the way it usually does with it's cities, by giving birds eye views for scale, but then keeping the camera heavily controlled so that you never quite know where you are in proximity to things.