Is absolutely recommended to walk from one place to another since all the locations are museums or churches.
To visit the sites mentioned it takes about 4 or 5 hours, it depends on the time you decide to visit a site.
The itinerary of Rome to discover the places of Christianity: a journey through the Vatican Museums and St Peter's Basilica to know the great works of the world's most famous artists, the history of the church and the Popes and many other interesting findings.
To reach the Vatican City you have to take the subway line A and stop at "Ottaviano". The first stage are the Vatican Museums. Inside the museum you will have the opportunity to visit several areas, including the Gregorian Egyptian and Etruscan Museum, the Art Gallery, which houses works by famous artists such as Caravaggio, Bernini, Giotto and Raphael. After visiting the Vatican Museums go to St. Peter's Square, take some pictures outside the large and suggestive square, with its high obelisk, temple of Christianity, and prepared to visit the St Peter’s Basilica. The church of Rome, considered one of the world's largest Papal Basilicas, contains the “Pietà” by Michelangelo. After visiting the basilica, with its beautiful nave and the big altar, return to the square. At this point you can decide to take the subway or continue along the path along Via della Conciliazione and reach Sant' Angelo Castle, where you can visit the museum or stop for a break.