The best way to explore central Naples or the historic district of Spaccanapoli is by foot. Most historic and cultural sights are located within a compact area of approximately 3 X 3 kilometers or 1.5 X 1.5 miles, with the exception of Pompeii , Herculaneum and Mount Vesuvius . Getting around Naples by car can be a challenge. Many roads were built during the Medieval period, and can be very narrow, one-way, and hard to navigate. Parking can be difficult to find and expensive. Luckily, Naples offers a complete system of public transport including buses, subways, funicular railways, and trams. Tickets (biglietti) can be purchased at tabacci (tobacco/convenience) shops and some newsstands, and must be validated when beginning your journey. Options include 90 minute timed tickets (1.10 euro) and daily passes (3 euro). 

UnicoCampania have recently made available some handy PDF maps for their various bus, metro, train and train services. There are five in all - including one with suggested ways for getting between key points around the city. To download one or more, start from the new 'Maps' link on the first of their English pages, here: http://www.unicocampania.it/index.php...

Metro (subway) lines #1 and #2 crisscross most of the city center, with Garibaldi, Museo, and Montesanto stations serving as major connection points. Metro line #1 connects Cavour & Museo stations (for the National Archeology Museum ) with the Vomero hilltop and northern suburbs. Metro line #2 connects Garibaldi/Napoli Centrale train station with Montesanto transfer station, Mergellina (2nd ferry port), and Pozzuoli (port + Roman amphitheatre). Near the Montesanto and Piazza Amedeo stations, you can also transfer to funicular railways leading to Vomero. Montesanto is also the transfer point for the Cumana & Circumflegrei train lines running westward into the suburbs, while at Garibaldi/Napoli Centrale, you can transfer to the Circumvesuviana train for Pompeii and Sorrento . Other metro lines to Capodichino airport and the University are under construction.

City buses can be ridden using the same 90 minute 1.10 euro Unico Napoli ticket (biglietto). Useful tourist routes include the R2 from Garibaldi/Napoli Centrale to Piazza Municipio across from Castel Nuovo & Naples’ main port, Molo Beverello - however ANM have stopped the 3S bus that used to run to and from Capodichino airport, a route which is now served only by the special Alibus.

Taxis are available at Capodichino airport, Molo Beverello port, Garibaldi/Napoli Centrale train station, and a few taxi stands around the city. Use caution as overcharging in taxis is frequent. Flat rates can be requested at the beginning of a journey.

Another option is the "hop on, hop off" tours (3 different routes for one price), which leave from Piazza Municipio next to Castel Nuovo, across from the main Molo Beverello port. Tickets are about 20 euro and can be purchased onboard.

The Artecard includes unlimited public transport on some versions of the card and free or discounted admission to popular tourist sights. If you plan to visit several museums and cultural sights, it can be a good deal. Sales points for the Artecard include Capodichino airport, Napoli Centrale train station, most tourist offices, and major sights such as Pompeii and the National Archeology Museum .

The Artecard quite difficult to get hold of.... the most reliable is the outlet in the tourist office at the train station.

It is however, excellent, a great way to get around, although sometimes the routes are confusing, and long walks can be needed.

If going to Pozzuoli , don't use the line from Garibaldi, it involves a long walk down a steep hill.

Use the Circumflegri line, which stops close to the port.