Water seems more abundant in Rome than in most large cities. There are many wonderful fountains besides the enormous Trevi fountain. I liked the Seahorse fountain commissioned in 1791 by Prince Marcantonio Borghese when he renovated the Borghese gardens. Fountains like this combine two of my loves: art and flowing water.
starting in ancient times. The ancient Romans built many aquaducts to provide water to a city that reached a million inhabitants. There were many public baths; the Baths of Caracalla were the largest and by one estimate could accomodate up to 6000 people at one time.
Any water watching enthusiast visiting Rome should try to make the day trip to Villa d'Este in Tivoli.
Villa d'Este, a UNESCO World Heritage Site was built in the Renaissance by Cardinal Ippolito II d'Este after he tried and failed to become pope. Water is everywhere; the cardinal really got carried away. The fountains are all fed by gravity; no pumps are used. Part of the water comes from a river that is partially diverted and some of it comes from a spring.
In one part of the garden there is long row of fountains and each of the many heads that spout water seems to be different.