This bridge you see is called an aqueduct. It is used to transport clean water between Roman cities, because raw sewage leaks into the rivers so some people got sick and died.
We have drank the water from the river... and now we are sick due to the raw sewage that has leaked into the water.
Rome’s government finally decided to build tall bridges with an arch-like design which ran clean water through all Roman settlements; allowing fresh water to be efficiently distributed throughout the Roman settlements. The first Roman aqueduct was established in 312 BC.