Catanzaro's cathedral stands in Piazza Duomo at the heart of the historic upper city. The current building dates primarily from 1951 — rebuilt after the great 1783 earthquake that devastated much of the original medieval city, followed by further reconstructions after a 1832 quake, and the World War II bombing. What you see today is mid-century Italian ecclesiastical architecture rather than the medieval original.
The interior contains some surviving treasures from earlier churches: a polyptych by Pietro Negroni (16th century), which is one of the more important paintings in Calabria; and various accumulated pieces of silverwork and religious art. The piazza outside is a good place to understand Catanzaro's topography — the city spreads across a ridge with dramatic drops on both sides, and the cathedral square sits near the highest point.