[4] It was a seaside retreat for the Roman elite, as reflected by the extraordinary density of luxurious houses featuring lavish use of coloured marble cladding.

Buildings of the ancient city include the Villa of the Papyri and the so-called "boat houses", wherein the skeletal remains of at least 300 people were found.

In the 2nd century BC the city walls were built (between 2 and 3 metres thick), constructed primarily of large pebbles, with the exception of the coastal section made of opus reticulatum.

It participated in the Social War (91–88 BC) on the side of the "Allies" against Rome and was defeated by Titus Didius, a legate of Sulla.

It lay hidden and largely intact until discoveries from wells and tunnels became gradually more widely known, notably following the Prince d'Elbeuf's explorations in the early 18th century.

The course and timeline of the eruption can be reconstructed based on archaeological excavations and two letters from Pliny the Younger to the Roman historian Tacitus.

[8] At around 1 pm on the first day of eruption, Mount Vesuvius began spewing volcanic material thousands of metres into the sky.

After the plume had reached a height of 27–33 km (17–21 mi),[9] the top of the column flattened, prompting Pliny to describe it to Tacitus as a stone pine tree.

The prevailing winds at the time blew toward the southeast, causing the volcanic material to fall primarily on the city of Pompeii and the surrounding area.

The first pyroclastic surge, formed by a mixture of ash and hot gases, flowed down the mountain and through the mostly-evacuated town of Herculaneum at 160 km/h (100 mph).

A succession of six flows and surges buried the city's buildings to approximately 20 m (66 ft) depth, causing little damage in some areas and preserving structures, objects and victims almost intact.

However, other areas were damaged significantly, knocking down walls, tearing away columns and other large objects;[10] a marble statue of Marcus Nonius Balbus near the baths was blown 15 m (49 ft) away and a carbonised skeleton was found lifted 2.5 m (8 ft 2 in) above ground level in the garden of the House of the Relief of Telephus.

He appointed the Italian military engineer Giovanni Antonio Medrano and Roque Joaquin de Alcubierre to supervise the extensive new project.

The discovery of neighbouring Pompeii, substantially simpler to excavate due to a smaller layer of material covering the site (4m as compared to 20m at Herculaneum), diverted attention and effort.

[19] From 1927 until 1942, Amedeo Maiuri conducted a new campaign, sponsored by Mussolini's regime, which unearthed approximately four hectares which today are part of the archaeological park.

Due to bradyseism, which affects the entire Vesuvius region, portions of the historic city of Herculaneum today lie as much as 4 metres below sea level.

The entrance opens directly onto the atrium, but the ruins are not well preserved due to damage caused by previous excavations.

The second house in insula II takes its name from a lost fresco of Argus and Io that once adorned a reception room off the large peristyle.

A highly adorned biclinium (a dining-couch for two persons[23]) with frescoes in the fourth style and a spacious triclinium originally marble-floored are found off the atrium.

It is thought to have belonged to consul Lucius Calpurnius Piso Caesoninus, Julius Caesar's father-in-law, who was a patron of poets and philosophers and built there the only ancient library that has survived virtually intact.

[24] The same techniques could be applied to the rolls waiting to be discovered in the as-yet unexcavated part of the villa, eliminating the risk of potential damage from unrolling.

[27] In 2024 the winners of a contest called the Vesuvius Challenge, with the help of AI, managed to reveal hundreds of words across 15 columns of text, corresponding to around 5% of a scroll.

The last inhabitants waiting for rescue from the sea were probably killed instantly by the intense heat of the pyroclastic flow, despite being sheltered from direct impact.

A study of victims' postures and the effects on their skeletons seemed to indicate that the first surge caused instant death as a result of fulminant shock due to a temperature of about 500 °C (930 °F).

A scientific study, published in 2021, showed that chemical analysis of the remains was able to provide further insights into the health and nutrition of Herculaneum's population.

In contrast to Pompeii, where casts resembling the body features of the victims were produced by filling hollowed spaces of the body imprints in the ash deposit with plaster, the shape of corpses at Herculaneum could not be preserved due to the rapid vaporisation and replacement of the flesh of the victims by the hot ash (ca.

[35] The volcanic ash and debris covering Herculaneum, along with the extreme heat, left it in a remarkable state of preservation for over 1,600 years.

However, in 2001, the Packard Humanities Institute began the Herculaneum Conservation Project, a private–public partnership initially set to provide financial aid to local authorities addressing critical issues.

However, after working in tandem with the Getty Museum, conservators have created a technique where solvents are used to remove some of the wax and lessen the buildup on the walls so that the paint no longer chips off.