Sentence:  Roriczer begins, “If you wish to draw the <WSD>groundplan</WSD> for a pinnacle, according to the stonemason's art and with the correct geometry, then begin by drawing a square, as it is shown here with the letters a, b, c, d.” 
Meaning of the word marked with <WSD> tags:  A diagram, usually to scale, showing the layout of the ground level of a building or other physical structure; floorplan.