<human>:  Why did the Romans use aqueducts?
<bot>: The Romans used aqueducts to transport water to their cities. Aqueducts were also used to transport water to places outside of the city, such as the baths. Aqueducts were built to transport water to places outside of the city walls, and were often constructed in a way that allowed water to flow downhill. This allowed water to flow into the city from a higher elevation, rather than having to carry water uphill.