An apostolic see is an episcopal see whose foundation is attributed to one or more of the apostles of Jesus or to one of their close associates. In Catholicism the phrase, preceded by the definite article and usually capitalized, refers to the See of Rome.
Tertullian (c. 155 − c. 240) gives examples of apostolic sees: he describes as churches "in which the very thrones of the apostles are still pre-eminent in their places, in which their own authentic writings are read, uttering the voice and representing the face of each of them severally" the following churches: Corinth, Philippi, Ephesus, and Rome.
Tertullian says that from these "all the other churches, one after another, derived the tradition of the faith, and the seeds of doctrine, and are every day deriving them, that they may become churches. Indeed, it is on this account only that they will be able to deem themselves apostolic, as being the offspring of apostolic churches".
See also: Papal supremacy
By a long-standing usage, evidenced already in 431, when the Council of Ephesus, the third ecumenical council, employed the phrase "our most holy and blessed pope Cœlestine, bishop of the Apostolic See", the expression, "the Apostolic See", is used in the singular and capitalized to mean specifically the see of Rome in reference to the Pope's status as successor of the Apostle Peter.
In Catholic canon law, the term is applied also to the various departments of the Roman Curia. The Code of Canon Law states: "In this Code the terms Apostolic See or Holy See mean not only the Roman Pontiff, but also, unless the contrary is clear from the nature of things or from the context, the Secretariat of State, the Council for the public affairs of the Church, and the other Institutes of the Roman Curia." The bodies in question are seen as speaking on behalf of the See of Rome.