Pizzighettone's big attraction is its well-preserved rampart wall, which still encircles its small historic centre. The walls were designed in the 12th century (though a garrison dates back to Etruscan times, in the fifth century BC), and expanded and improved over the subsequent centuries.
The walls are full of casemates (fortified gun emplacements), vaulted chambers used for housing supplies and weaponry. Several of these chambers have been turned into an exhibition space dedicated to local trades, with implements of farmers, fishers, cheese-makers and blacksmiths on display. A section of the walls also functioned as a prison, used at various times between 1785 and 1954. You can peer inside the dismal chambers. There's even graffiti marking the days spent in isolation left by one young prisoner (Luigi Iannacone) in 1943. Iannacone was imprisoned for refusing to fight in WWII. His attempted escape ended badly, and he was later shot against the prison walls.
If you can't make a guided tour, you can wander much of the area at any time.