Everything Pompeii is, except smaller, better preserved, and with 90% fewer tourists. Buried by superheated volcanic mud, the city retained upper floors, wooden beams, mosaics, even food. 20 minutes from Naples.
Napoli Garibaldi → Ercolano Scavi. Exit, walk 500m downhill, you're at the entrance. That's it.
Circumvesuviana, 20 min, €2.60. One of the most rewarding 2-hour experiences in Italy.