I visited this WHS in November 2018 focusing on 2 locations out of the main 3 inscribed, namely Pompeii and Villa di Poppea di Oplonti. I'll definitely visit Ercolano in the near future as the I have no doubt that it is on par with the 2 locations I visited which were top WHS.

I allowed a full day for Pompeii and parked next to the entrance/exit at Camping Zeus. Even though Pompeii is always visited by tour groups with their infamous antenna rod and all kinds of soft toys, the site is so big and vast that it didn't feel too crowded, especially first thing in the morning when most would be gobbling their included breakfasts. Make sure to pick up a free map from the information office before entering as it's quite confusing otherwise to find your bearings at first.

Pompeii is truly an intact (although crumbling) ghost town from Roman times with an extraordinary setting at the foot of the culprit volcano of its destruction as a living town and a great opportunity to understand the 'ordinary' day-to-day life during Roman times. At Pompeii, you get to experience the whole ensemble of Roman architecture: temples, villas, houses, shrines, stores, necropolis, mosaics, frescoes, stucco, thermal baths, water management, outposts, roads, amphitheatres, etc.

Out of all this outstanding site, the absolute highlight of my visit were definitely the intricate and colourful murals and frescoes. The best ones in my opinion were those at the Villa dei Misteri (the farthest from the entrance and the first recommended place I'd suggest to visit before the crowds), the Casa dei Vettii (quite close to the cafeteria and toilets), the Casa del Menandro, the Casa del Frutteto and the Palestra dei "Iuvenes". The peculiar Priapo mural with an oversized phallus at the entrance of the Casa dei Vettii symbolises the economic prosperity of the domus' owners.

If you're after the unmistakable Pompeii colours of the frescoes, make sure not to miss the second inscribed location of Villa di Poppea di Oplonti in Torre Annunziata which is practically similar in size to the Villa dei Misteri. The first Sunday of each month, entrance to all historic monuments is free! The National Archaeological Museum in Naples has several other frescoes from Pompeii and Herculaneum apart from various artefacts.

Another impressive aspect are the Pompeii casts. Liquid plaster was poured in the empty moulds left in the ashes of the pyroclastic flow of the volcano. Impressive expressions of the victims of Pompeii were caught by this technique in the tragic instant of their death. Very recently a tiny graffito from before the Pompeii disaster was discovered showing that the eruption must have taken place in autumn rather than in summer. It can be seen at Regio V at the Casa con giardino in Pompeii.

All in all this is yet another top WHS in Italy. PS: next to the entrance to Villa Oplontis, there is a UNESCO inscription marker.