The Palatine Gate (above) is pretty much what is left of Roman Turin. The northern entrance to the old city, it has been, as you might guess, substantially restored, with extensive works during the 15th century. It was due to be demolished in the 18th as part of a major redevelopment, but an architect and engineer saved it. Fortunately - because it is one of the most impressive sights in the city, and you can see it free. You might even get a nicer day than I did.
* Belated thanks to Stanmore & District u3a for hosting my talk on my book Assassins' Deeds. A history of assassination from ancient Egypt to the present day (Reaktion books). There was a good audience who asked some interesting questions.