Being awarded the titular title of a suburbicarian see is considered more an honor or prestige than aimed towards a functional intent.
The increasing involvement of the cardinal bishops in the administration of the papal curia resulted in a detachment from their dioceses.
Therefore, some of them, in particular the cardinal-bishops of Sabina and Velletri, have for centuries had auxiliary bishops and in 1910 Pope Pius X's apostolic constitution Apostolicae Romanorum made this practice obligatory for all suburbicarian dioceses.
For the diocese of Ostia – the titular diocese of the Dean of the College of Cardinals – no resident diocesan bishop was appointed; it is entrusted to an apostolic administrator, which is always the Cardinal Vicar of Rome.
This article about a Roman Catholic titular see in Europe is a stub.