Mount Vesuvius is a stratovolcano in the Gulf of Naples, Italy, about 9 km (5.6 mi) east of Naples and a short distance from the shore.
Vesuvius is best known for its eruption in AD 79 that led to the burying and destruction of the Roman cities of Pompeii, Herculaneum, and several other settlements. That eruption ejected a cloud of stones, ash, and fumes to a height of 33 km (20.5 mi), spewing molten rock and pumice at a rate of 1.5 million tons per second. It ultimately released a hundred thousand times the thermal energy unleashed by the Hiroshima bombing. [source]
Vesuvius has erupted many times since and is the only volcano on European mainland to have erupted within the last hundred years. Today it’s regarded as one of the most dangerous volcanoes in the world because of the population of 3 million people living nearby, making it the most densely populated volcanic region in the world. [source]