|Visited Pompeii and Herculaneum. Pompeii had 20,000 people killed by sulphur dioxide fumes and then they were covered by ash. Herculaneum residents were covered with molten lava in 79 A. D. Today 3 million residents live around Mt. Vesuvius. It is Italy's most dangerous volcano and our guide said that experts can predict activity 7 days in advance. He hopes that they are right.