I guess you have to define what you think is risky. To me it means the danger of getting caught. But just having sex in an old underpass that nobody uses any more isn't very risky.
This one to me hits the nail on the head. Two guys fucking behind a hedge at the Louvre museum in Paris. You can see right at the when they first start fucking in the hedges a guy almost runs right into them. Whoever is filming holds the camera high so that you can see all the people nearby. That to me is risky.
https://thegay.com/videos/1485298/sex-in-paris/