We are arriving in Rome March 24th, we will be at the city center of Rome at aprox. 10am, we will be there until about 3pm, what is nearby that my sister and I (and maybe some of the group) could do. We like anything new, we probably will be pretty tired from the flight so not so much walking.
Rome is a really beautiful city to just wander around, with amazing art and sculpture in every church and on every corner. If it is your first time there, and your time is limited, I would take in the Piazza Navona, Trevi Fountain, Spanish Steps, Pantheon and maybe the Borghese Gallery and Museum.
There are plenty of walking tours that are worth doing also.
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Go to the Borghese Gallery and Museum gardens for a stroll. Pretty awesome way to get away from the craziness of Rome.