I was delighted to learn about this, as the lovely Annina Teatime and myself did that exact same thing when we went to Rome together some years ago. Sant’Andrea, Palazzo Farnese, Castel Sant’Angelo – we went to the locations of all three acts.
Here’s a photo of me and Annina’s friend F., doing a Scarpia/Tosca tableau in front of the Roman prison:
Annina and I came to the same conclusion as Ross, by the way, concerning Tosca’s jump from the Castel. I love Ross’ idea of a sequel. Jessica Duchen has since elaborated on the idea in a great post pondering the possibility of other opera sequels.