The term Holy See comes from the Latin Sancta Sedes, meaning Holy Chair, and originates from the enthronement ceremony of the Bishop of Rome, the Pope. Strictly speaking, the cathedra, i.e. the chair or throne, represents the position and authority of the Holy Father or a bishop, and the place where he resides in the territory of his jurisdiction. Here the Holy See refers to the seat of government of the universal Church. Geographically, this seat of government is located in the Diocese of Rome. In terms of actual governance, the Holy See refers specifically to the position of the Holy Father, who by reason of his office as Vicar of Christ, namely, and as pastor of the entire Church, has full, supreme, and universal power over the whole Church, a power which he can always exercise unhindered (Dogmatic Constitution of the Church, #22), and by extension the Curia, which consists of the Secretariat of State, the Council for Public Affairs of the Church, the Sacred Congregations, tribunals, and other institutions and offices (Code of Canon Law, #360). The Holy See is also interchangeable with the term Apostolic See. The Code of Canon Law provides the following definition:
The term Apostolic See or Holy See applies not only to the Roman Pontiff but also to the Secretariat of State, the Council for the Public Affairs of the Church, and other institutions of the Roman Curia, unless the nature of the matter or the context of the words makes the contrary evident (#361).
The term see, from the Latin sedes, is actually the technical term for all dioceses and the places of residence for their bishops. For example, Bishop Loverde is the Bishop of the See of Arlington and his cathedral of residence is the Cathedral of St. Thomas More, also in Arlington; the cathedral also houses the bishops cathedra or throne. Originally, sedes designated the Churches founded by the Apostles, and later limited particularly to the five great patriarchal sees: Rome, Alexandria, Antioch, Jerusalem, and Constantinople; interestingly, to this day, these latter four patriarchs follow the Holy Father in honor.
This understanding and ordering is reflected in the pronouncement of the Popes: For example, Pope Gelasius I (492-496) declared, Est ergo prima Petri apostoli sedes (i.e. Therefore, the first is the seat of the Apostle Peter). In the Liber Pontificalis of Pope Leo III (795-816), the following prescript is recorded: Nos sedem apostolicam, quae est caput omnium Dei ecclesiarum judicare non audemus (We dare not judge the Apostolic See, which is the head of all the Churches of God). Clearly, the terms Holy See and Apostolic See evolved to refer specifically to the authority of the Holy Father and Rome.
Interestingly, each February 22, the Church celebrates the Feast of the Chair of St. Peter. To celebrate the feast of a chair at first hearing, sounds strange. However, the chair refers to the primacy and authority our Lord entrusted to St. Peter, which together are a unifying strength for the whole Church; so, really the Holy See is what is celebrated and honored. This primacy and authority are symbolized by the monument of the chair of St. Peter located against the wall of the apse behind the main altar in St. Peters basilica sculpted in bronze by the artist Bernini; the sculpture is a reliquary for what is traditionally believed to have been the original chair or cathedra of St. Peter. Again, what is of importance is not so much the actual chair, but what that chair symbolizes the Holy See.