Rising above the city, the Janiculum Hill is often mistaken as one of Rome’s original seven hills, but this is not the case. It is, however, the second highest hill in the city after Monte Mario and is celebrated for its breathtaking panoramic views. On clear days, visitors can take in sweeping vistas of Rome from its slopes. Sometimes, overgrown trees can block the view, but simply walking a little way down the hill reveals equally impressive sights.
From the Janiculum, one of the highlights is the striking view of St. Peter’s dome, which is visible from the far side of the piazza. The area itself carries historical significance, with both the square and the road leading up named after Giuseppe Garibaldi. He famously commanded Italian forces against the French here in 1849. Throughout the piazza, visitors will also find several statues that commemorate this moment and honor the individuals involved in the city’s storied past.
Source - https://en.wikipedia.org/wiki/Janiculum