Italy at night

You mean in Rome, or in other cities too? In Rome, Piazza del Popolo's scale doesn't make it particularly relaxing, I'd say.

I meant to put Rome

We enjoy Piazza Navona in Rome
More relaxing and atmospheric than P Popolo

Piazza di Santa Maria in Trastevere is the most atmospheric place to me during my stay in Rome. Piazza Testaccio and Piazza di Pasquino are also notable places in Rome to relax.

To reinforce your choices -

Campo de Fiori -

By day, it's a lively, colorful outdoor market. By nightfall, it's transformed into a hangout from locals, kids, and travelers alike. Side streets (like little alleys) have a ton of places to sit and have a drink; people watch; browse little shops.

If you catch the (professional) street musicians who usually play near the statue of Giordano Bruno, you're in for a treat!

When I first caught them at Piazza della Rotonda - The Pantheon - I was hooked. The lead singer started out with some haunting melodies I had never heard before. He played keyboards and his band mates accompanied with their own individual instruments. They play for a long time.

When I heard them at Piazza Navona and Campo de' Fiori, they played a mix of pop and rock - some Led Zeppelin (Stairway to Heaven was popular), some George Michael and a few other artists.

Trastevere -

Yes, a good choice for your list - it will be fun with a funky, bohemian vibe. They have traditional and innovative Trattorias, craft beer pubs and artisan shops. With the Passeggiata, a crowd hangs around the Piazza di San Calisto and Piazza Santa Maria - there is a mosaic-filled church.

It would help if you would clarify a bit what you are looking for. It sounds like you want a laid back piazza as opposed to one where there's a lot of activity. Is that right?. Are you looking for small or large? Will you want to be sitting at a restaurant, or do you just want to hang out?

Piazza Navona , pretty and relaxed. From there, you can stroll to the Pantheon which is neat at night.

A great place to see at night is the Foro Romano and the Coliseum. Very ghostly, as if you were looking back 2000 years. Find a quiet place and let your mind wander. I traditionally end my night's meanderings with a gelato and sitting on the steps of Sant' Agnese just staring at the Bernini fountain in Piazza Navona. Guaranteed to give you a very peaceful night's sleep.

sitting on the steps of Sant' Agnese just staring at the Bernini fountain in Piazza Navona. Guaranteed to give you a very peaceful night's sleep.

Agreed. It's true, most of the Piazzas, when lit up, offer their own awe-inspiring beauty and relaxation.

One of my little experiences was - one night I made my way to Piazza Navona (after getting a Panino and extras at Coop.) I sat on a bench, ate my food, and admired the fountains in a "new light."

Fountains have their healing properties in different ways. Also that same evening, echoing softly around the Piazza, was the music of the street musicians I had heard before.

The Trevi Fountain, in all its majestic glory, is absolutely gorgeous when lit up at night - taking on a different persona.

One of my favorite spots in Rome is Terrazza del Pincio, which overlooks Piazza del Popolo. You have to walk up quite a few steps to get there from the back of Piazza del Popolo, but the view is worth it.