Cathedral, in Christian churches that have an episcopal form of church government, the church in which a residential bishop has his official seat or throne, the cathedra. Cathedral churches are of different degrees of dignity. There are cathedral churches of simple diocesan bishops, of archbishops or metropolitans, of primates, patriarchs, and, in the Roman Catholic Church, of the pope. A cathedral church is not necessarily large and magnificent, although most cathedrals have become so. Since the territorial organization of the early church followed that of the Roman Empire, cathedrals from the first were established wherever possible in towns, not in villages. In the early European Middle Ages, the town in which a cathedral church was situated became known as the cathedral city.
In the Roman Catholic church, canon law makes no architectural conditions for a cathedral. The only canonical requirement is that a cathedral should be consecrated and adequately endowed. The pope has the right to designate a cathedral, although the choice of the bishop of the diocese or his decision to build a cathedral is normally approved by the pope. The bishop must be present in his cathedral on certain holy days, and he must normally perform ordinations there.
In the Eastern Orthodox church the cathedral is the main church in a city where the bishop resides and where he celebrates the liturgy on festival occasions. In Russia, where the dioceses have always been few and have covered a vast area, the main church in any large town became known as a cathedral (sobor), even though no bishop was in residence there. The principal church of a big monastery also assumed the same name.
After the 16th-century Protestant Reformation, cathedrals where bishops were rejected became simple churches. In Sweden the cathedral continued to be the seat of the Lutheran bishop. In the Church of England, where the order of bishops was retained, the cathedrals remained as the seat of the bishop.