Pompeii is obviously a well-known ancient Roman city, and as such has quite a lot of area to explore.
You will need at least a couple of hours to explore the ruins. At Pompeii, you should visit the Forum, Lupanare (a brothel), and amphitheater.
The ancient Pompeii forum was the center of religious, cultural and political life in the ancient city. The amphitheater of Pompeii is the oldest surviving Roman amphitheater, and was buried by the eruption of Vesuvius in 79 AD, which also buried the entire town of Pompeii. The amphitheater was home to gladiatorial contests, and was also the site of a deadly brawl between Pompeiians and residents of Nuceria, which resulted in a 10-year ban on such events.
In order to get there, take the train from Stazione Termini. Naples Another must-see is Naples, and if you are feeling highly ambitious you could likely see both Pompeii and Naples in the same day. While there, you should visit the Museo Archeologico Nazionale and see the classical art on display and to see the Cristo velato (Veiled Christ) sculpture by Giuseppe Sanmartino. You can also climb Mount Vesuvius, which is the only volcano in Europe that has erupted in the last 100 years. The hike will take you about a half an hour and is not said to be particularly challenging. While in Naples you can also visit the San Gennaro Catacombs, which features a network of tunnels and passageways that are lined with graves that date back to ancient history. There are said to be over 3,000 grave sites. In order to get there, take the train from Stazione Termini.