Rising 4,000 feet above Italy's Campania region, Mount Vesuvius is one of the world's most active volcanoes, unleashing its lethal fire time and again. We examine the 79 A.D. eruption that destroyed the city of Pompeii, sealing the volcano's place in history; a 1631 eruption, at the height of the Black Plague, when the fiery mountain killed around 18,000; and a 1944 eruption that killed 26 as WWII raged across Southern Italy. Is Vesuvius in a resting period or gearing up for another explosion.