This modern museum brims with the treasures of Nikopolis: Roman marble statuary, mosaics from Byzantine churches and more. Abundant English-language explanations help envision life (and death; there are lots of funerary monuments) in the city, as well as the massive naval Battle of Aktion, for which the city was built. The ticket price includes admission to the archaeological site.
The museum is just north of Preveza; take any Ioannina- or Filippiada-bound bus, and ask to be let off at the stop out front. From the museum, it's another 1km north to the main entrance to the site.