Final answer:
The Romans used arches to distribute weight by transferring it from the top downwards and outwards through voussoirs, culminating at the keystone, resulting in durable and expansive structures such as the Colosseum and aqueducts.
Step-by-step explanation:
The Romans used arches to distribute weight by transferring weight evenly downwards and outwards. When an arch is constructed, the weight from the top of the arch is redistributed down to the sides, transferring through the wedge-shaped stones called voussoirs down to the ground. This structural principle allowed for larger interior spaces free of columns or other intrusive supports, which in turn led to the development of larger and more complex architectural structures like aqueducts, vaults, and domes. Notably, the true arch construction technique was pivotal to this design, as the keystone at the center holds the voussoirs in place, creating an incredibly durable and long-lasting structure. Historical examples of Roman use of the arch include structures such as the Colosseum and the vast network of Roman aqueducts. By placing arches side by side to form arcades or back to front to form vaults, and eventually spinning the arch on its axis to create a dome, the Romans were able to create expansive, breathtaking interior spaces such as seen in the Roman basilicas and the iconic Pantheon.