Sometimes, large churches are loosely called “cathedrals.” Thus, there are occasional references to St. Peter’s Cathedral in Rome. However, while St. Peter’s Basilica (or, to be strictly accurate, The Papal Basilica of St. Peter in the Vatican) is generally regarded as the largest church in the world, it isn’t properly termed a cathedral.
Size has nothing to do with whether or not a church is a cathedral. While most cathedrals are large, some are not. The real question to be answered in determining if a church fits the formal definition is whether it is the home church, or the “seat,” of a bishop. In Latin, the chair of a bishop, the episcopal throne, is known as a “cathedra,” from the Greek “kathedra,” meaning “seat.” (That’s why a pope speaking officially is said to speak “ex cathedra” or “from the throne.”) The principal church of a diocese possessing such a physical throne is called a “cathedral.”
Enormous though it is, St. Peter’s Basilica in the Vatican is not the headquarters church of the Pope, whose official title is actually Supreme Pontiff or Bishop of Rome. (The English word “pope” derives from the Greek “pappas” and the Latin “papa,” both meaning “father.”) As Bishop of Rome, the Pope has his cathedral, instead, in the Archbasilica of St. John Lateran — officially, the Cathedral of the Most Holy Savior and of Saints John the Baptist and the Evangelist in the Lateran. (The Emperor Constantine confiscated the property of the ancient Roman Laterani family and gave it to the Bishop of Rome; the church’s name remembers this.) St. John Lateran stands 2.5 miles to the southwest of Vatican City. Even so, as the Cathedral of the Bishop of Rome — that is, of the Pope — it outranks all other Roman Catholic churches in the world, including St. Peter’s Basilica.
St. John Lateran was originally dedicated by Pope Sylvester I in 324 but has been renovated and extended many times since then. Moreover, from 324 until 1309, when the French Pope Clement V moved the seat of the papacy to Avignon in France (where it remained through most of the 14th century), the popes lived in the adjacent Lateran Palace.
Today’s St. John Lateran is scarcely small: It’s approximately 460 feet long and 240 feet wide. (For comparison, the main structure of the Salt Lake Temple measures 184 by 117 feet.) But St. Peter’s is 720 feet by 490 feet — making it wider than St. John Lateran is long. And yet St. Peter’s is still not a cathedral.
Perhaps another way of illustrating the distinction between “cathedral” and “large church” is to consider the history of the so-called “Crystal Cathedral” in Garden Grove, California. From its completion in 1981 (as the largest glass building in the world) until 2013, it was the principal worship location of a Protestant group called Crystal Cathedral Ministries and the point of origin for a weekly television preaching broadcast called “Hour of Power.”
Founded in 1955 by evangelist Robert Schuller, the group belonged to the Reformed Church in America. Before moving into its “cathedral,” it had held its services in both a rented former Baptist church and a nearby drive-in movie theater. Rev. Schuller was not a bishop in any sense and, thus, while “Crystal Cathedral” is very large, it was never really a cathedral at all in the technical meaning of the word.
However, after filing for bankruptcy, Crystal Cathedral Ministries sold the building to the Roman Catholic Diocese of Orange — that is, of Orange County, California — in 2012. Since then, the church has been substantially renovated, particularly in its interior, to accommodate Catholic liturgy. On July 17, 2019, it was consecrated and formally renamed as Christ Cathedral. The head church of the Diocese of Orange, and thus the official seat of the Bishop of Orange, it has now become a genuine cathedral for the first time in its history— although its size hasn’t significantly changed.
Obviously, these are matters of names, of semantics. With a floor area of 240,000 square feet, St. Peter’s Basilica is generally reckoned the world’s largest church despite not being a cathedral. The Conference Center of the Church of Jesus Christ of Latter-day Saints in Salt Lake City, however, has a floor area of 1.4 million square feet. It’s certainly not a cathedral. But is it a church? And could every Latter-day Saint ward chapel be called a cathedral, since each has a bishop?
Daniel Peterson founded the Middle Eastern Texts Initiative, chairs The Interpreter Foundation and blogs on Patheos. William Hamblin is the author of several books on premodern history. They speak only for themselves.