The region around Naples, one of the most physically unstable areas of high population in the world with a long history of volcanic activity and earthquakes, suffered one of its more devastating events on this day in 1626.
An earthquake that it has been estimated would register around seven on the modern Richter scale struck the city and the surrounding area.
Its epicentre was about 50km out to sea, beyond the Bay of Naples and the island of Capri to the south, but the shock waves were strong enough to cause the collapse of many buildings in the city and the destruction of more than 30 small towns and villages.
A tsunami followed, in which according to some reports the sea receded by more than three kilometres (two miles) before rushing back with enormous force, towering waves engulfing the coastline.
In total, it is thought that approximately 70,000 people were killed by the quake itself and the tsunami.
Naples at the time was a thriving city, still under Spanish rule. It had a population of around 300,000, which made it the largest port city in Europe and the second largest of all European cities apart from Paris, which had about half a million inhabitants.
It was enjoying a golden age in expansion, particularly at the more expensive end of the property market, with many luxury estates springing up in the Chiaia district to the north of the city.
Construction of the Royal Palace, the masterpiece of the late Renaissance architect Domenico Fontana, was almost complete. Overlooking the Bay, the palace would for many years be the main residence of the Bourbon kings.
However, bordered to the south by Vesuvius and to the north by the steaming, bubbling Campi Flegrei (Phlegraean Fields), the city was under constant threat from seismic activity. In Naples alone, between 10,000 and 20,000 people were thought to have been killed on July 30, 1626.
Indeed, the 1626 quake came during one of several periods punctuated by deadly events. There had been three earthquakes in one year in 1622, sparking a wave of activity that was perhaps behind the substantial eruption of Vesuvius that took place in 1631. It was the first of any consequence for four centuries, resulting in the deaths of between 3,000 and 6,000 people.
Another earthquake in 1693 claimed the lives of 90,000 in the wider region. Earthquakes and eruptions were so frequent in the next century that 110,000 people were killed in one 75-year stretch between 1783 and 1857, equating to 1,500 every year.
There has not been an eruption of Vesuvius since 1944 and the last major earthquake to hit the region was in 1980, when a tremor measuring 7.2 on the Richter scale took place in the province of Avellino, its epicentre 85km east of Naples, with a death toll of 2,914.
Nowadays some three million people live in and around Naples and although the last few decades have been calm, seismologists say there is little reason to be complacent.
Work began on the construction of the Royal Palace in Naples in the early 17th century. The main part of the building, including the façade that opens on to the Piazza del Plebiscito, was completed by 1620 and additions were made over time, including the connecting Teatro San Carlo, the famous Naples opera house, which was opened in 1737.
For a less strenuous volcanic experience than climbing Vesuvius, the volcanic crater Solfatara, just outside Pozzuoli, is a worthwhile alternative. Part of the vast Campi Flegrei, a volcanic area with a four-mile diameter, Solfatara is fascinating for its active emissions of volcanic ash that form piles of yellow tuff rocks and for the fumaroles releasing sulphorous steam.