You'll probably spot Cathedral of Todi across town before you actually find this grand building. Rest a while inside if the doors are open or just take in the facade from outside.
If you're spending a while in Todi, Cathedral of the Santissima Annunziata is a good place to start your sightseeing. This principal church is one of many attractions that'll keep you occupied here. Santuario dell'Amore Misericordioso di Madre Speranza, Santa Maria della Consolazione, and Porta Catena are also ready to be explored nearby.