The major structure built by the Romans to transport water to cities was the aqueduct. Aqueducts were engineering marvels that allowed for the movement of water from distant sources, like rivers or springs, into urban centers, providing essential supplies for drinking, bathing, and irrigation. The most famous example is the Aqua Appia, constructed in 312 BC. The design employed gravity and arches to maintain a steady flow, and many aqueducts included elaborate bridges and tunnels. These structures were crucial in sustaining large populations in Roman cities, showcasing the engineering prowess of the Roman Empire.