My Raeford, a half lab half border collie rescue, loved tennis balls better than anything except trucks (to ride in, not fetch). When we were together, my house had a simple shallow A roof. I would toss the ball onto the roof and Raeford would listen for it rolling down, then catch it when it came off the eaves.
If I threw it too hard and it went over the peak, he'd go around the house and get it when it didn't come down.