A cathedral is the principal church of a diocese. The name is derived from the bishop’s cathedra, or throne, situated at the end of the apse, behind the altar, so that the ministrant faces the congregation. If the altar is set against the wall, the cathedra is on the Gospel side. A cathedral may be designated metropolitan, primatial or patriarchal, according to the authority of its bishop. Cathedrals are the setting for the most solemn liturgical celebrations, such as ordinations, the chrismal mass on Maundy Thursday, the feasts of particular churches, and the papal masses with apostolic blessing on solemn feast days.