Basements, according to national codes and standards, are poured in three phases. Footers serve as the stabilizer for the entire structure. To be able to withstand the weight of the structure, footers need to be a specific width according to the American Concrete Institute. Typically a 24" wide footer will handle most residential projects. Footers need to go down deep enough to reach the soil horizon - depth in which the home is free from soil movement issues.
The second phase in basement construction is the forming and pouring of walls. Foundation walls can be built with a variety of materials, with concrete being the strongest. Wall thickness and rebar content are based on the specific needs of the structure being built and the substrata lateral pressures it is subjected to. In the trade, 8 inch - 10 inch walls are typical.
Lastly, according to code, is the basement floor. The basement floor is the non-structural component of the basement, meaning the floor is a walking surface only. The basement floor does serve as constraint for the bottom of the wall against the outside lateral forces, i.e. the force of the dirt.
2405 Rogers Avenue has completed the three construction pour phases - footers, walls and floor - as well as, waterproofing and partial backfill. Framing and floor trusses are needed to provide the lateral strength prior to completing the backfill.
3726 Aviemore is a very interesting job. You will find the house has two partial basements, one on either side, connected by a crawl space. In addition, there is a 12 foot customized concrete wall that adds interest and individuality (See pictures below).
319 E. College Street is an example of a 100 year old house being given new life. You can see the house that has been moved off in the background and a crawl space being formed and poured. This will be a fun job to watch as the construction progresses to the final phase.