The city of Pompeii was an ancient town-city near modern Naples in the Italian region of Campania, in the territory of the Comune of Pompei, at the mouth of the river Sarno (ancient Sarnus). Pompeii, along with Herculaneum and many villas in the surrounding area, was mostly destroyed and buried under 4 to 6 m (13 to 20 ft) of ash and pumice in the volcanic eruption of Mount Vesuvius in 79 AD. Researchers believe that the town was founded in the late VII-early VI century BC by the indigenous Osci (or Oscans) under the influence of the Etruscans on a hill already settled in the Bronze Age. After a long period of domination by the Samnites started in the late Vth century BC, the city was conquered by the Romans and became a Roman colony (Colonia Cornelia Veneria Pompeianorum) in 80 BC after it joined the unsuccessful rebellion (bellum sociale) against the Roman Republic. By the time of its destruction, 160 years later, its population is esteemed to be approximately 10,000-15,000 people, and the city, occupying an area of about 66 hectares inside the walls (45,2 excavated), had a complex water system, a theatre and an odeion, an amphitheatre, baths, gymnasium and a port. The eruption destroyed the city, killing its inhabitants and burying it under tons of ash. Evidence for the destruction originally came from a surviving letter by Pliny the Younger, who saw the eruption from a distance and described the death of his uncle Pliny the Elder, the admiral of the Roman fleet based in Misenum, who tried to rescue citizens. The site was lost for about 1,500 years until its initial occasional rediscovery in 1599 and broader rediscovery almost 150 years later by the Bourbons of Naples in 1748. Since then, the excavations have been continued until today constituting one of the most famous and relevant examples of research and management of archaeological sites. The objects as well as the buildings decorations, mainly the fresco wall paintings, that lay beneath the city have been well-preserved for centuries. These artefacts provide a chronological reference and an extraordinarily detailed insight into the life of a city during the early Roman Empire. Since 1863 the method invented by Giuseppe Fiorelli of fill in by liquid plaster the voids in the ash layers that once held human bodies allows to have casts of the dead Pompeians in the exact position the persons were in when they died. Pompeii has been a tourist destination for over 250 years. Today it has UNESCO World Heritage Site status and is, after the Roman Coliseum, the second most popular tourist attractions in Italy, with approximately 3 million visitors every year.