Or you might do things that are not listed.
In 2002, there was a trip to Scandinavia. In Bergen, we had a free afternoon and the PD asked if we'd be interested in seeing Edvard Grieg's house. Some of us were, and we chipped in a couple of dollars each to get a van and driver to take us there. For me, at least, it was one of the high points of that trip. It was just as he'd left it and it felt as though he'd be walking in the door at any minute. I said as much to the docent, and she replied that was the effect they wanted it to have.
And if you are in Moscow later in the summer when it gets dark, there's the Moscow by Night city tour. Where all the buildings and monuments are lit up. It's not on any itinerary, but if the weather is clear and it gets dark around 10 or 11, they take you on a bus to see them.