I used the dirt from my backyard to build our pizza oven. I poured a concrete foundation, a rammed earth base and a concrete slab on top of that to build the oven on. Instead of buying an expensive imported oven my kids and I made 2x4x6 inch bricks and built a dome. First I mortared standard split firebrick to the concrete slab for the oven floor then I built the dome and arch. The chimney is built from the same sun-dried mud bricks. I put a precast concrete cap on top of the chimney then stuccoed the dome and the chimney. We have been using the oven for 5 or 6 years now and the bricks have shown no deterioration from the repeated firings.