As the major attractions are all located relatively close together, walking is the best mode of transportation for exploring Rome. Taxis and buses are also available, but traffic can be heavy and may add to travel time.
Prices for taxis start at €3 and increase based on distance, time of day and number of passengers. Buses are a more affordable option at €1.50 for a single ride or €6 for a day pass. However, buses can be crowded and may add to travel time due to traffic.
If you have more time, consider adding a visit to the Roman Forum or the Spanish Steps. If you have less time, consider removing Piazza Navona from your itinerary. It can easily be added to your visit to the Pantheon.