On our first day in Rome, having arrived in the morning after a layover redeye flight, we walked the neighborhood a bit to get a sense of what was around. 
Following the river, we eventually hit the bridge of angels leading to Castle Sant Angelo.
There was no line at all, and there was room on the next guided tour, so we bought our tickets and showed ourselves around while waiting for the tour to start.
The castle is a great example of Roman philosophy on “reusing” historic architecture. What originally started as emperor Hadrian’s family tomb turned into Paupel apartments and a prison.
They still have a decent amount of artwork and artifacts, including some crazy utilitarian weaponry and a sculpture by Raffaello de Montelupo.
Per usual, we tried to read every sign and learn whatever we could about the place, which was fortuitous because it proved helpful for us to have a better experience on our tour. 
The castle winds up and around to a topmost viewing point. Throughout there are a lot of open “windows” offering a great view of the city and sometimes the Vatican. There is also a cafe near the top, with tables lining the walls, and some lovely ivy growing and spilling over.
On the private tour, we saw several closed-to-the-public rooms, including an oil storage room, some prison cells, and the Pope’s private bath.
Our tour guide was wonderful and the group was very small, only 6 people, so it was very easy to ask questions (and squeeze into some small spaces).
The prison cell was pretty spooky. Our guide said that at some points there could be thirty prisoners in a room about the size of a large bathroom. I asked about the management of those prisoners (how do they get fed, etc), and she alluded that they probably fought for rats passing by. š·š¤¢
We had never even heard of Castle Sant Angelo, so stumbling upon this gem was a great way to start off our trip, and a very good dive into some of the city’s history. If you get the chance, take the small groups tour.
Love,
PD
making life an adventure 