If you've seen La Dolce Vita by Fellini you'll
recognize this spot easily. The fountain lies in a small piazza
off Via del Tritone. It was designed by Nicola Silva. Legend goes
that by throwing a coin in the fountain you can secure your return
to Rome (we didn't do it, but I still have hopes to return). We
went there in the afternoon; we were not looking for the fountain,
just wandering the streets and ended up here. It was extremely
crowded, almost imposible to get near the fountain. I don't know
which hour is better, my guess is that it is crowded all the time.
Maybe early morning will be a better time if you wish to avoid the
crowds.