The Piazza Navona, Pantheon, and Trevi Founter are close together and it's easy to walk from site to site.
I added a map from Google below to give you an idea of the distance between sites. The Spanish Steps are a little farther away but if you have time, you could walk to it while you are in the area. We didn't have time to see it since we had to catch a plane
Since we were so short on time, we took a taxi, instead of the bus, to the Piazza Navona. I have seen this piazza is so many movies so it was on my to-see list while we were in Rome. It is also a great starting point for visiting the Pantheon and Trevi Fountain since they are just a short walk from there.
The main attraction of the Piazza Novana are the three fountains with Fontana dei Quattro Fiumi or Fountain of the Four Rivers (1651) by Gian Lorenzo Bernini being the most famous. Giant statues symbolize what were considered the world's four greatest rivers: the Nile, the Ganges, the Danube and the Rio de la Plata. Each statue also represents one of the four continents that were known at the time. The giants rest on a large rock that rises from a circular basin and are surrounded by animals and flora of the respective continents.
CHIESA DI SANTA MARIA MADDALENA
We stumbled upon Chiesa di Santa Maria Maddalena on our way to the Trevi Fountain. This Baroque era church is not far from the Pantheon and it's easy to overlook because of it's simple exterior.
Don't be fooled. This hidden gem in the middle of Rome has an interior that is full of stunning motifs and beautiful ceiling frescoes.
On our way to the Trevi Fountain, we passed through this area. I have no idea what this building is but it was so beautiful. Hopefully someone will see this post that will be able to enlighten me.
We took a taxi to the Piazza Navona since we had to catch a plane and wanted to see as much as possible. There are buses that will stop nearby but no Metro station. The cost of the taxi was around €15 which was a good deal for us since taking the public bus takes a while to get anywhere because of the many stops it makes.
We also took a taxi back from the Trevi Fountain since it would drop us off at the apartment we rented. If you are on a tight schedule, I suggest taking a taxi.