Rome is famous for its fountains.
The most popular and the grandest of Rome's fountains is by far the Trevi Fountain which has become famous from the movies Three Coins in a Fountain and Fellini's La Dolce Vita. It is a very large and glorious fountain located very close to the Pantheon. The fountain was built to mark the construction of the frist aqueduct about 1,800 years after the aqueduct was built. The Trevi Fountain was completed in 1762 by Nicola Slavi and it is literally part of the building, surrounded by windows.
The fountain looks like a stage from a theater. In the middle is the figure of Neptune standing on a huge shell, pointing down with his hand to steps covered with water and two Tritons with horses blowing into the shells. Neptune stands inside of a small arch. On either side of the arch, there are large columns with a female figure on each side, the whole fountain looks like a huge portico with the balcony on top with large plaque and heraldics of Clement XIII.
Spend a little bit of time here, enjoy yourself, look at the fountain, and drop some money into it so that (as legend has it) you can always come back.