The Cathedral
The chair and the mother church.
Not the largest church of a diocese, nor the oldest, nor the most beautiful, though it is often all three: the church of the chair.
The cathedra
A cathedral is the church that holds the cathedra, the chair of the bishop, and from that chair it takes its name. The Council teaches that the bishop is to be considered the high priest of his flock, and that the pre-eminent manifestation of the Church is found in the full, active participation of all God’s holy people in the same liturgical celebrations, especially in his cathedral church.1
There the bishop presides at the sacred liturgy; there, in the week of the Lord’s Passion, the holy oils used in every parish of the diocese are consecrated at the chrism Mass;2 there his priests are ordained and gather around him. Whoever stands in a cathedral stands at the visible center of a particular church.
Co-cathedrals, pro-cathedrals, basilicas
Where dioceses have been joined, or a see moved, a diocese may have a co-cathedral sharing the dignity of the chair; a pro-cathedral serves as cathedral where none has been erected. A basilica is a different honor altogether: a title conferred by the Apostolic See, or held from time immemorial, binding the church that bears it in a particular way to the Church of Rome.3 The four major basilicas stand in Rome; minor basilicas stand throughout the world. Some cathedrals are basilicas also; neither dignity implies the other.
All of these are marked in the register of cathedrals and basilicas, country by country, each with its own record.