Il Passetto is the Medieval pathway that connects the Vatican palace to the Castel Sant’Angelo. Most of the time, visitors don’t even notice it– but if you’ve approached the Vatican from Prati (which is the neighborhood with the Ottaviano metro stop) then you’ve gone through an archway that was supporting Il Passetto. Most of the year Il Passetto is closed, but in the later summer (typically July-September), the passageway is opened up with regular admission to the Castel Sant’Angelo–but get this–it’s only open at night!! So, not only is Castel Sant’Angelo creepy and evocative by night (and it’s also great to visit anytime), you get to pretend you’re a pope fleeing from the invading Holy Roman Emperor’s army! How fun is that?
It’s basically the funnest. It’s not a million degrees because it’s night. It’s not crowded because a lot of people don’t know you can do this–even for people visiting the Castel Sant’Angelo, there’s not a big sign or anything pointing you to the Passetto, so I’m sure lots of people go without actually walking the pathway–and if feels secret and cool and you get a whole new view for the iconic Dome of St. Peter’s shots. Walking the Passetto is one of the best ways I know to win at your Rome trip. The only way to top that is to get a tour of Monte Testaccio, which even I haven’t been able to swing yet…
For info (in Italian, but it can probably be switched to English?) go here: http://www.castelsantangeloestate.it
So worth it.