The Museo Archeologico Nazionale is a wonderul Museum to wonder through!  However it is important to check ahead if you want to see specific items--whole sections of the Museum such as the Pompeii mosaics may be closed for restoration for days, weeks, or years.

To complement your trip to Pompeii, this museum has a great Mosaic display, and a 'special' room dedicated to the brothel art work found in Pompeii. The Museum also features many of the original frescoes from Pompeii and many of the artifacts found at Pompeii and Herculaneum.  Also on permanent display are the Farnese Collection of Greek and Roman (mostly) statuary including the Farnese Bull and Farnese Hercules.

During the year there are temporary exhibits. This past winter, exhibits included artifacts and statues from another city burried by Mt. Vesuvius'  erruption in 79AD: Ercolano. There is also a permanent Egyptian Exhibit that is usually closed.

Many Roman artifacts are on display at this museum, from glassware, to coins, and models of their buildings. The Museum is open 9am-7:30pm but closed on Tuesdays.  Admission is  8,00 Є but it is included in the Artecard, which can provide free or reduced admission to various sights around Naples. http://sights.seindal.dk/sight/1073_N...

How to get to the Archaeological Museum from the train station:

While you can take a cab from the taxi stand in front of the station, it is very easy (and cheaper) to get to the museum on the metro. Both Line 1 and Line 2 of the Naples metro depart from Central Station and have a stop near the Museum (line 1 stop is called "museo" and is the nearest, line 2 stop is called "Cavour" and is 250 meters away, but there is an undergound connection with a pedestrian conveyor belt).

 Purchase a Uniconapoli ticket (1.30 euro as of 2014) from a newsstand in the station, and follow the signs for “Linea 1" or "Linea2" or the "M" of Metropolitana. For line 2, go one stop in the direction of Pozzuoli to the Cavour station.  In this station, you will see a sign that says “Museo,” which points to a long tunnel. The tunnel is well lit, perfectly safe, and has a moving walkway. Make your way up to street level and you will be right outside the museum. For line 1, go four stops to Museo station.