Sean Adcock wrote to me recently and told me he had been trawling through pics for an upcoming talk in South Korea at the Jeju Peace Forum and came across this photo montage he and Sunny Weiler took when they found this interactive "arch thing in some castle type building somewhere".
He hoped it would make me smile. Of course it did.
Even with a limited number of voussoir shapes there is sometimes more than one way to build an arch.
