|"Is this all real? Or has this been happening inside my head?"
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Mount Vesuvius is a volcano in the province of Naples in Italy. In 79 AD, Zaccaria Innocenti made inappropriate use of the Tarantallegra spell, "conjuring a 'dance' within [the mountain]." It is unknown whether this meant he cast the spell on himself and danced around inside Mount Vesuvius's crater, or cast it on the volcano itself, thereby provoking the major eruption it had that year. This disaster destroyed the Roman cities of Pompeii and Herculaneum, killing at least 1500 people, which possibly included Innocenti.