The middle of the house was the high point and the perimeter was lower in elevation all around. 

What are your favorite parts of the city and your favorite neighbors and perimeters you like to stay in and why?

This could be a stem wall or, more likely, building up the outer perimeter of the back yard 3-4 feet with retaining walls on both sides and having a two tier back yard.

Structural walls are perimeter walls that are supporting the house.

When you look at a house built on slab, you will want to ascertain whether the slab was insulated (and how much); whether there is a vapour barrier under the slab; what nature of footing was poured at the perimeter; and, if applicable in your area, if any measure to address radon have been implemented. 

I have a duplex with a detached garage that has a slab (not in the greatest shape, several cracks), but the structure itself sits on concrete block surrounding the perimeter of the slab.

I use Huntwise Pro to find all boundaries (spent $700. on one survey only for the surveyor to tell me my stakes were right on line with his tools within 6 ")  and study county maps and easements, which ranchers and the few part time cabin owners  out there just make their own easement/roads  and everybody, the few people around, like myself with an illegal easement on one of the 40 acre properties I bought apart from a tax lien  accept to be accommodating to neighbors in rough territory where you cannot traverse the legal easements on the perimeters so therefore, would have no access to your property.   

Around the perimeter where the weird gutter system was. is destroyed, but removing the rotten wood and replacing with new wood doensn't seem to be a big deal.I wasn't swimming when I walked through, lol, so no flood type damage.

Our multi is rural so we had to put bait stations around the perimeter.

There is a city sidewalk along the perimeter of the yard that is adjacent to the street.