I have to go out of town for work so the boys will stay at Grits' breeder while I'm gone. Her house backs up to a hill. The yard is fenced except for the very back which is a natural rock wall going straight up. They also had to build a fence to keep dogs from getting on the back roof of the house.
Last time I returned from travelling, I went to get the boys and Grits was standing on the peak of the house roof watching me pull in the driveway. He figured out how to get under the fence!