All these exhortations Jesus gave during his teaching about the end of the age have a Jewish bent. Housetops were used in that region as a place for leisure in the cool of the evening. You could dine, relax, sleep, store goods, and pray on your home's flat roof. And Jesus had already said it was the citizens of Judea who should flee when the abomination of desolation occurs. Many Christians, when the armies of Titus began arriving at Jerusalem, did flee the city before the greatest destruction came.