To get to the first stop on this itinerary, take Metro Line A to Flaminio, then hike up the stairs on the eastern side of piazza del Popolo.
The pincio terrace and its beautiful view over the city await you at the top. From here, Piazza napoleone, you can see a little bit of everything in the historical center, from the Vittoriano on the left to the transmission towers of RAI television on the right.
The big dome in the center, across the river, is St. Peter’s Basilica, the largest church in the world and, at 150 meters, the tallest building in Rome. Looking just to the left of that dome, you will seen the massive brick wall circuit that defines the Vatican City. From this high perspective you really get a sense of the fortress-like aspect of the city of the popes.