For those not sure what they're looking at and wanting to know...
The house will basically have no internal load bearing walls, so all the weight of the roof is on the external ones. So they have dug big holes where the weight will go and filled them with concrete.
On top of this surface, on each side of the starter bars (the steel bars sticking up) will be built a brick wall, basically like a double brick wall with the starter bars in a gap between the two.
The very inside will be filled with dirt and then a concrete slab will be poured over the top. On top of that will be where our frame etc is built.

Kind of like this picture, but with the double wall section.