 It's brick. It was put in in brick, and I thought I just needed to tuck point it, but as I started looking at it, I realized that some of the bricks are actually starting to bow out, and I probably need to fix it. But when I looked into it and started looking into it, the bottom part of the foundation is only a single layer of bricks thick, like from the bottom of the cellar up about four feet, and then they basically made a normal brick wall two bricks thick.