What's the must-see thing in Sorrento?

Pompeii sits 27 km east of Sorrento. The Circumvesuviana train from Sorrento station costs €3 to €4 each way and drops you at Pompei Scavi, Villa dei Misteri station. The Porta Marina entrance is a 2-minute walk downhill. Get there before the first tour buses arrive around 10am. The city was founded around 600 BC and the eruption preserved roughly two-thirds of the original settlement, still being uncovered today. The stone streets carry wagon ruts worn into the basalt over millennia. The smell of wild fennel and warm dust hits before you're past the first block. Shade is limited to the roofed Forum Baths and the House of the Faun, so bring 1.5 litres of water per person. The Villa of the Mysteries near the northwestern edge holds the coast's single best ancient artwork. A 17-metre frieze of Dionysiac initiation rites covers an entire room, the pigments still a deep Pompeian red.

Herculaneum is the better site. That sounds like heresy when Pompeii is 10 times larger, but the preservation here is on another level. The pyroclastic surge carbonised wooden furniture, food, and a library of papyrus scrolls at the Villa of the Papyri. You can see second-storey balconies intact, mosaic floors with their original colour, and the wooden partition screens in the House of the Wooden Partition. The site is compact enough to cover in 2 hours, and visitor numbers tend to be a fraction of what Pompeii draws. From Sorrento, the Circumvesuviana to Ercolano Scavi takes about 50 minutes. A combined ticket for both sites runs around €22, valid for 3 consecutive days, so you can split visits across two mornings without rushing either. The excavation pit sits below modern Ercolano. You descend a ramp into the town, the temperature drops a few degrees, and the acoustics change. Street noise fades. You hear your own footsteps on Roman flagstones.

The Blue Grotto on Capri is the third pick and the most weather-dependent. Hydrofoils from Sorrento's Marina Piccola reach Capri's Marina Grande in 20 minutes for roughly €20 each way. From there a motorboat takes you to the grotto entrance, where you transfer into a wooden rowboat that holds 4 passengers. The boatman pulls you through a 1.3-metre-high opening by grabbing a chain fixed to the rock. The hull scrapes stone as you duck. Inside, refracted sunlight turns the water an electric blue that photographs poorly and looks unreal in person. The grotto visit costs about €18 on top of the ferry. The catch is weather. Waves above half a metre close the entrance, and the grotto stays shut roughly 30% of days between October and April. In September you'll likely get in. Worth noting, Capri itself charges nothing to walk. The Augustus Gardens cost €1, and the view from there toward the Faraglioni rocks is the best free lookout on the island. Skip the funicular cafe at the top and bring a cornetto from a bakery on Via Roma instead.

Sorrento proper is a base, not a destination. Piazza Tasso is the central square, loud with Vespas and lined with souvenir shops selling limoncello in ceramic bottles shaped like lemons. The town's best moment is the 10-minute walk from Piazza Tasso down to Marina Grande, the old fishing harbour on the north side. The path drops steeply through a stone archway, and the harbour still smells of diesel and salt and drying nets. A plate of spaghetti alle vongole at one of the harbour restaurants costs €14 to €18, the clams tiny, briny, and cooked in white wine with garlic and peperoncino. Better than anything on Piazza Tasso. But don't spend your days in Sorrento when Pompeii, Herculaneum, and Capri are each under an hour away by train or ferry. Solo-traveler safety scores 7.2 out of 10 (see the TTDI Solo-Safety Index), and the biggest practical risk is the steep cliff paths down to the marinas, not crime.