Why Arches Rule

Roman aqueducts still stand after 2,000 years. The secret: an arch converts all downward force into compression along its curve. Every stone pushes against its neighbor, and force travels outward to the ground.

Remove the keystone — the wedge at the top — and everything collapses. That single piece locks all others in mutual compression. The arch does not fight gravity; it redirects it.

Any material that resists being squeezed can form an arch. No glue, no mortar — just geometry doing the work. Modern engineers still use arch principles in bridges spanning hundreds of meters, proving that the Romans got the physics right two millennia ago.