Mount Vesuvius looms across the bay from Naples, 5.6 mi (9 kms) away from the city. It is the only mainland European volcano to have erupted in the last hundred years although it is currently sleeping. Most famously it erupted in 79 AD, burying Pompeii and Herculaneum in ash, killing an estimated 10,000 to 25,000 people.
Today it is still regarded as one of the most dangerous volcanoes because 3 million people live nearby and Vesuvius' eruptions tend to be explosive rather than gentle. The last eruption was in March 1944 which destroyed several nearby villages.