It's more than 45 years since Vatican II - the Second Vatican Council.
What is Vatican II?
On 11 October, 1962, Pope John XXIII opened a universal meeting of bishops, in Rome, with the intention of opening up the Catholic Church and its teachings to the wider world.
It was a global ecumenical council meeting and, as such, Pope John XXIII invited observers from other Christian Churches.
It ran for four consecutive autumns (concluding under the watch of Pope Paul VI in 1965) although specially formed commissions met throughout the year to reflect on the discussions and to prepare for the next session.
Nearly 3,000 men (the Council Fathers) were entitled to seats on the Council.
What did it aim to do?
The Second Vatican Council aimed to define, clearly, the role of the Church and also that of her bishops.
Its purpose was also to encourage dialogue, openness and engagement with the modern world.
The council's documents offer guidance for dialogue with the world's other faiths and cultures not to mention the promotion of unity amongst Christians.
Another major change saw renewal of the Liturgy (the way Catholics worship) and a new approach to interpreting the Bible was approved.
This is a simple overview of Vatican II - see below for more details of the Council's documents.
Dei Verbum
Dogmatic Constitution on Divine Revelation
Lumen Gentium
Dogmatic Constitution on the Church
Sacrosanctum Concilium
Dogmatic Constitution on the Sacred Liturgy
Gaudium et Spes
Pastoral Constitution on the Church in the Modern World
Gravissimum Educationis
Declaration on Christian Education
Nostra Aetate
Declaration on the Relation of the Church to non-Christian Religions
Dignitatis Humanae
Declaration on Religious Freedom
Ad Gentes
Decree on the Mission Activity of the Church
Presbyterorum Ordinis
Decree on the Ministry and Life of Priests
Apostolicam Actuositatem
Decree on the Apostolate of the Laity
Optatam Totius
Decree on Priestly Training
Perfectae Caritatis
Decree on The Adaptation and Renewal of Religious Life
Christus Dominus
Decree Concerning the Pastoral Office of Bishops in the Church
Unitatis Redintegratio
Decree on Ecumenism
Orientalium Ecclesiarum
Decree on the Catholic Churches of the Eastern Rite
Inter Mirifica
Decree on the Media of Social Communications