What's the most public place you've had sex

Wife's best friend she grew up with and is still very close friends with told my wife that she and her then boyfriend were at her dads company picknic when they got to wanting to play. They went down this trail and when they thought they were safe dropped her swim suit bottom and bent over and her boyfriend got behind her and they were going at it when they heard a noise and there stood her mom. Her mom told her "you two hurry up I can't stand guard here forever" She said her mom and one of her dads friends were watching. When they got done her mom said "Now you can watch out for us"
 
My wife and I have fucked at Black's beach in San Diego. It was in a semi secluded area but there were still people watching. My wife liked that several men were watching and masturbating. I took her doggy style.
 
The most public place wife had experienced sex, well, if you mean open spaces then it was around the trees of a belvedere/lookout near where she lived while single.

But public in the sense of risky and exposing was in a bus station with a man she used to go out (already married).

Both of us (husband and wife) it probably occured sometimes we had sex in tree parks.