When Christina says the arches were cut out, they were literally cut out. The masons put up a rectangular frame and then blocked straight across, with a lintel positioned above where the arch would be. Then they traced a plywood semi-circle directly onto the block (front and back). Then they took a router with a straight 2″ bit and cut on the line on both sides. About three inches of block connection remained, and they simply knocked this out and smoothed it with a rasp. This material is so fun to work with.
Christina worked out the ratios and radii of the arches, and I think they are perfect. Their heighth lends an elegance that I probably would not have gotten right. Good job, Hon!