Teramo's cathedral is the main monument of the city, a substantial Romanesque-Gothic building begun in 1158 and extended over the following centuries. The lower facade and the portal by Diodato Romano (1332) are the most striking exterior features; inside, the cathedral is a calm three-naved space of bare stone with two outstanding medieval artworks.
The 1430 Jacobello del Fiore polyptych above the high altar and Nicola da Guardiagrele's silver-gilt altar frontal are both world-class works of late medieval art. The Crypt of San Berardo holds the relics of the city's patron saint. Free entry; allow half an hour.