the.com/arch
It holds itself up by leaning together — gravity weaponized into grace.
self-lockingEach stone pushes inward, so it can't collapse
keystoneThe last wedge placed makes the whole thing stand
roman flexAqueducts crossed valleys on stacked arches for miles
no mortar neededPure geometry can hold dry stone for millennia
strongest curveCatenary arches carry their own weight perfectly