It is a temple of strong gothic characteristics with three naves and a transept that holds the main altar. It has an ogival door and stained-glass windows, and it underwent profound changes in the 18th century that gave it a Baroque appearance, reflected in the bell tower and in the side door.
Inside, there are four altarpieces and a chapel, as well as an important tumulary collection, of which the tomb of King João II, who was buried there between 1495-1499, stands out. It was the seat of the bishopric until 1577.