Catholic–Orthodox Joint Declaration of 1965
The Catholic–Orthodox Joint Declaration of 1965 was read out on 7 December 1965, simultaneously at a public meeting of the Second Vatican Council in Rome, and at a special ceremony in Istanbul. It withdrew the exchange of excommunications between prominent ecclesiastics in the Holy See and the Ecumenical Patriarchate of Constantinople, commonly known as the Great Schism of 1054.
Source: Wikipedia — Catholic–Orthodox Joint Declaration of 1965 (CC BY-SA 4.0)