In addition to public fountains, where else was water directed after reaching an ancient city?

The answer centers on the importance of water in ancient urban life, particularly in relation to public baths. After flowing into a city, water was essential not only for drinking and irrigation but also for social and hygienic purposes. Public baths, often central features of ancient cities, served as places for bathing, socializing, and conducting business. They required significant water supplies, which would have been directed to them to support these functions.

Public baths were often elaborately designed with sophisticated plumbing systems to cycle and heat water, reflecting the engineering prowess of the time. The baths served both practical and cultural functions, helping to enhance public health as well as fostering a sense of community among residents.

In contrast, while the other options like city walls, public temples, and trade centers were crucial components of ancient cities, they did not serve the same direct and communal role regarding water. City walls were more defensive structures, public temples were primarily religious sites, and trade centers facilitated commerce but did not have the same immediate requirement for water as a public bath would. Hence, the significance of public baths in urban planning and daily life makes them the correct answer in this context.