The Octagon is made of bricks – four hundred thousand of them. We know the number of bricks because of the carefully preserved billing records kept by the contractor. Why are so many homes in the Washington area made of brick? If you live somewhere in the Piedmont region of the Middle Atlantic states and you garden, you know that the primary ingredient of the local soil is clay. Readily available, cheap to make, easy to transport, strong, capable of being molded into various size and shapes, and fireproof, brick was the choice not only for this architect, but for those who built up and down the East Coast – and not just for houses, but for walls, sidewalks, and commercial buildings. The Octagon’s bricks may have been made at the nearby brickyard on Lafayette Square, the site which produced 5000 bricks a day for the President’s House, completed in 1800.