The Geometric Door

With the shape of an octagon in the top half, and a ripple of concentric circles in the bottom, both inside rectangular panels, this well-used door seems like a geometricist's dream. With everything else running along an (almost) vertical centre-line, from the handle, letter box, spy hole and polyfilla filled white blob, it thus comes as a surprise that the house is number 13 - an uneven number.