A plaque just outside remembers June 30, 1944. That night, Nazi forces were planning to blow up the arch to slow the Allied advance. To save their treasured landmark, Volterrans ripped up the stones that pave Via Porta all'Arco and plugged the gate, managing to convince the Nazi commander that there was no need to blow up the arch. Today, all the stones are back in their places, and like silent heroes, they welcome you through the oldest standing Etruscan gate into Volterra. Locals claim this as the only surviving round arch of the Etruscan age; most experts believe this is where the Romans got the idea for using a keystone in their arches.