The few acres of Julius Martial, more blissful than the gardens of the Hesperides, sit on the long escarpment of the JANICULAN...The opening lines of Martial 4.64 seem pretty clear: we're nowhere near Monte Mario. Instead and straightforwardly we are on the Janiculan ridge, that beauty-spot where, to this day, Romans love to promenade and take the evening air. To have a villa here, serene above the smoke and noise pollution of the city below, is to live the dream -- it always was. And the views are amazing. Two minutes into Paolo Sorrentino's The Great Beauty they kill a tourist, they're that lovely. You really do feel you can see everything, which made it a favourite viewpoint for the panoramic prints of Rome brought back by aristos from the Grand Tour.
It is a long escarpment, and lines 5-8 seem to steer us to the northerly part of it, nearer the Vatican:
The flat summit, a moderate swelling, enjoys serener sky, shining with a light of its own while mist covers the winding valleys.The northern end gives us plenty of valley for the mist to fill: a big old cleft behind (west), a smaller in front (east), and the broad, flat gap to the north between the Janiculan and Vatican hills. It's no small interval: there was a Circus here in antiquity. The Via Cornelia wound through as well, on its way to Caere.
The obvious problem, though, is that even the northern end of the Janiculan is not where you'd go for a good view of Fidenae, Rubrae, or Anna Perenna. Or any view of them at all. You feel as though you can see everything from the Gianicolo, but actually you can't. We're far too far south.