What was a technological achievement of the Romans was the construction of what to convey water through valleys and cities?

What conveyed water to the cities was the aqueduct. What made the construction of long aqueducts which needed bridgework was the arch. The Romans were not the first to use the arch, but they were the first to make widespread use of it. Prior to the Romans, the arch was rare. The structural strength of the arch made the construction of large buildings and bridgework possible.