“What’s serendipity?” asks Claudio, dropping in on a conversation I was having with two clients on our AMALFI COAST tour.

“It’s the happy accident that brought us here,” I explain as we leave the gift shop at the end of an isolated bus parking lot, where we happened to meet the daughter of Andrea De Gregorio, the self-appointed “guardian of Vesuvius.”

Just an hour earlier, when zigzagging up the side of Vesuvius, Claudio had been recounting how the old Neapolitan tune Funiculì Funiculà was written to celebrate the opening of a tram that took 19^th century tourists to the top of the volcanic crater.

When descending, we decided on a whim to turn down a side road marked “Observatory,” just to explore. It led through a bus parking lot that dead-ended at a spectacular overlook facing the Bay of Naples. There was one lonely bar and tchochke shop selling miniature replicas of Vesuvius and cheap bracelets made of volcanic tufa. Several well-fed dogs slept in the empty lot. No other tourists were around.

After a Kodak moment at the overlook, Claudio waved us into the shop. “Come hear this history,” he said without elaborating.

Inside, a middle-aged redhead was waiting, holding the book VESUVIO, A VOLCANO & ITS HISTORY, by Elio Abatino. As she paged through the photographs, she launched into a history of tourism on Vesuvius, pointing out that this bar was on the exact spot where the funicular terminal once stood.

As it turns out, her father, Andrea De Gregorio, tended the ticket office for the two-seat cable car that replaced the tram after it was destroyed by the 1944 eruption, Vesuvius’ most recent. It was also severe, with lava flowing at 100 mph, debris hurdled three miles high, and ash falling as far away as Albania.

The beginning for the modern period of Vesuvius’ eruptions was the famous one in 79 AD that buried Pompeii. Before that, Mt. Vesuvius had been well behaved for about 15,000 years. The Romans saw it as benign, planting vines up and down its slopes, as seen in frescoes of the period. Pompeian wine was famous and sold far and wide in terracotta amphorae labeled “Vesvinum” and “Vesuvinum.”

Pliny the Younger offered the most vivid description of the 79 AD eruption in letters to Tacitus. (His uncle Pliny the Elder, in command of a fleet, perished while observing it from the sea.) From afar, Pliny the Younger first noticed a huge cloud that resembled a pine tree, rising straight up like a trunk, then branching out.. It then dropped back on itself from its own weight and spread out. Then ashes started to shower on the young writer.

“I turned and saw behind me a thick cloud that pressed upon us like a river, flooding the ground,” he writes. Night fell. “Not a cloudy, moonless night, but as if in a closed room when the lights are out. We could hear the moaning of women, the wailing of children, the shouting of husbands. […] There were those who, afraid of death, cried out for it.” Then he describes a clearing of air, followed by “a new darkness and a new cloud of thick ash.”

Modern scientists say the 79 AD eruption came in two phases: First was an eruption of pumice, ash, solid blocks, and gas that was propelled 17 km in the air. This fell and buried Pompeii in a couple of hours. A rain of finer ash smothered Herculaneum and other towns on the coast. Afterwards, groundwater flowed into magma chamber for 10 hours, causing a new eruption of different materials (a “freato-magmatic” process) and a shifting of the shoreline as the volcano swelled and rose up. A ring-like cloud of gases and ash formed and spread horizontally with the destructive speed of a hurricane, destroying everything in minutes. People who did not flee earlier died from suffocation due to the high temperature of the cloud of steam mixed with piroclastic material and toxic fumes. It was all over in 24 hours.

In the 19^th century, visiting Mt. Vesuvius was hard work. The first visitors traveled by pack animals on paths paved with large lava stones to the Atrio del Cavallo, where horses were refreshed and people rested before undertaking the ascent up the Great Cone by foot or on sedan chair.

Local farmers recast themselves as guides (“ciceroni”) and came armed with leather straps, ropes, and other devices to haul petticoated women and dandified men up the steep cinder slopes. Chaos ensued as their number increased.

To eliminate the inconveniences, a financier, Ernesto Enrico Oblieght, had idea of building a tramway in 1870. The funicular was completed in 1880, and the song Funiculí Funicula by Peppino Turco and Luigi Denza was the jingle written to publicize its grand opening.

That tram was subsequently destroyed three times by lava flows, and they finally threw in the towel after it was swept away by the 1944 eruption. The chair lift that replaced it in 1953 was ultimately discontinued a decade later, as the ascent was considered too windy to be safe.

So said the redhead and her book. And we wouldn’t have known any of this had it not been for that turn down Observatory lane. Sometimes it pays to follow a whim.