Hohenstaufen Emperor Frederick II's sharp-lined and blindingly white stone citadel was inspired by the Norman-style fortresses of Puglia. Frederick II built it here in the 1240s to remind the Pratese who was boss, and to defend the route from his homelands in Germany to his realm in southern Italy. While these days the inside is bare, you can climb onto what's left of the broken-toothed ramparts for a view of the city. Nearby is the newly restored 14th-century keep, the Cassero, Viale Piave (tel. 0574-26-693), once connected to the defensive wall by a viaduct until modern roads cut through it.